> If the only way a company can remove content is by suing

Not at all. I've already described elsewhere in this thread, at least twice now, what would happen in a sane legal regime, but I'll do so once more since this discussion is covering several subthreads.

Step 1: Company X complains to Company Y that content they are hosting is infringing Company X's copyright.

Step 2: Company Y sends Company X a copy of the legal document, sworn to under penalty of perjury, from the person who posted the content, that says they are the legitimate owner of the copyright to the content they posted. At this point, if Company X doesn't actually have a valid claim but is simply bluffing or pushing the envelope, nothing further happens.

Step 3: Company X, who believes they have a valid claim, presents evidence to Company Y that the content actually does infringe their copyright. For example, in the case described in the article, Casio (Company X) would present to Github (Company Y) the actual source code for their calculator, along with the evidence of how and when it was developed, and the details of the comparison of their source code with the content posted in the Github repository, showing why the latter must have been copied from the former.

Step 4A: Company Y looks at the evidence presented by Company X and decides it is legitimate. They send a notice to the person who posted the content saying that they have good reason to believe it infringes Company X's copyright, hence, pursuant to the contractual agreement already in place, the content is being taken down. Then, if the person who posted the content really is legitimate, they have to sue (but if they really were posting infringing content, nothing further happens since they know they won't win a lawsuit).

Step 4B: Company Y looks at the evidence presented by Company X and decides Company X is bluffing; they don't really have a valid claim but for some reason they are trying to get Company Y to comply. They tell Company X they do not believe the content is infringing. Then, if Company X really has a valid claim, they have to sue (but if they really were bluffing, nothing further happens since they know they won't win a lawsuit).

So the only possibilities for a lawsuit are in Steps 4A (if the person who posted the content really was legitimate and decides to sue) or 4B (if Company X really has a valid claim and takes it to court). But if either side really has a clearly valid claim (and at most one side can--either the content really is infringing or it isn't), the process is far, far more likely to stop at Step 2 or possibly 4B (if the person posting the content really is legitimate and the infringement claim is bogus) or Step 4A (if Company X really has a valid infringement claim and the person posting the content was bogus). The only cases that will make it to court will be the doubtful ones: for example, Company X really believes the content was infringing, but their method for comparing the source code is flawed and they don't realize it, and the person who posted the code really did independently invent it. Or the person who posted the content really believes the content was, say, fair use, but Company X thinks differently.

> I'd prefer if the latter category simply got a DMCA notice and went away, rather than having to go to court.

In my scenario, inadvertent infringers would stop at Step 4A. The difference between my scenario above and a DMCA notice is that, instead of just the bare assertion of infringement (Step 1 in my scenario), Company X now has to provide the actual evidence showing why the posted content is infringing. And Company Y has to judge that evidence. For inadvertent infringers, that does mean more work for both Company X and Company Y; but inadvertent infringement is precisely the case where you want some more work to be done to check the claim, because the person who posted the content is acting in good faith, so it's worth taking some more time to make sure they actually made a mistake.

By contrast, consider the scenario the DMCA is supposed to protect against, of a purposeful infringer, who just wants to post copies of videos of popular songs, for example, to boost their own YouTube following. First of all, this person now has to swear under penalty of perjury that the content they are posting does not violate anyone else's copyright, instead of just agreeing to a contract, so some percentage of people who would have been purposeful infringers in our current regime won't bother. Second, it won't take long for a company who owns copyrights to videos this person is posting copies of to get to Step 4A in my process above, at which point the videos get taken down. If it were just one video, the person might be able to convince YouTube that it was a mistake; but if they're really engaged in purposeful infringement, a single company could probably present, at once, a fairly large number of videos all of which were infringing, and all of which would get to Step 4A above. And at that point, YouTube simply shuts down that person's account. And once word gets around that that's how YouTube deals with purposeful infringers, the purposeful infringers realize that there is no value to be gained from doing it and stop. But again, Company X was forced to provide the evidence that yes, this really is a purposeful infringer, before the content gets taken down. They can't just assert it.

My scenario also means less work (no going to court) for the cases where Company X doesn't have a valid claim but is simply trying to bully. In fact, under my scenario, there is little to no expected gain from bullying at all, so companies would stop doing it, whereas under the DMCA, bullying is encouraged. And from what I can see, much if not most of the actual DMCA claims that companies are filing are bullying, not actual stopping of purposeful infringers.