I refuse to make you a screenshot of gmail, so I'll just ask: what are the contents of all those messages? You don't know, because your client allows you to read a message a time. Gmail lets you read a conversation at a time. Massive difference.

I fail to see a massive difference beyond extraordinary lazyness there.

I don't normally want to see a full thread at a time. It can make sense in a web-frontend where page refreshes take annoyingly long, but other than that I see more drawbacks than benefits in my workflow.

What I mean is that the atom of the mail client is an entire conversation. So when I move it to another folder (or label it in Gmail parlance) all the related messages get grouped, or flagged or whatever.

Again, that's nice but no difference to desktop mail clients.

There's nothing about conversations that prevents this. Look at Hacker News: it has both all-posts-on-a-page and nesting. Would you prefer that the comments view was just a list of timestamps and poster names and you had to individually click each one to see the comment? No? Yet that's what most mailing list clients and archives make you do.

You said "No" where I say "Yes". I have no problem pressing a single key between reading comments. I like seeing which comments I have already read. I like seeing which comments I have replied to. I like to flag comments that I might want to come back to later. I like archieving stuff, arranging it in folders or forwarding it by e-mail. I like attachments. Yes, I love all the features that have evolved in online discussion over the last two decades and would prefer if HN was a mailing list or newsgroup.

Unfortunately that's not mass compatible because most kids these days have unlearned what a newsreader is. Hence we are stuck with the poor substitute of a web forum (and not a particularly good one, as even PG will probably admit, unknown or expired link, eh?).

I'm not sure why you're so quick to condemn something that would be such a massive leap in usability for so many email users and that doesn't exclude your preferred method of operation.

I'm condemning it because it's a step backwards not forwards and affects me, as I have to deal not only with the outlook TOFU idiots but also with the gmail TOFU idiots now. Google of all companies should know better, but "fancy" won over "sensible" one more time.

But I want more. I actually wonder if the prevalence of mailing list-centric attitudes like yours among engineers is the reason we don't have mail clients with proper conversations yet.

It's called "clue". Engineers tend to also be the most extensive users of e-mail. Most mailing lists happen between technical people. Many E-Mail Clients are under active development. If conversation views were considered a worthwhile feature then we'd be having it everywhere by now. The implementation effort is minimal.

I actually suspect that it's still simply too hard: you have to sort and search potentially tens of thousands of messages just to display one conversation, and the easier route is just to make the human do the work. But I'd far rather my (or Google's) computer did it for me.

That's nonsense. Most MUAs are already tracking "conversations" as you call them and have done so for 20 years. It's just that most haven't bothered to display the threads in a "conversation view" way, because most heavy e-mail users [that I know of] don't find that view particularly useful.