On the contrary, this is not legacy, it is a new fashion.

The electronics and computers industries have been built initially based on free detailed documentation from all the manufacturers of components.

When I was a student in electronics, I learned more from datasheets and application notes than from most university manuals.

All companies continued to provide good technical documentation until close to the year 2000.

With the growth of the Internet I believed that it will become easier than ever to get technical documentation, as it could be now downloaded instead of having to get printed copies.

Unfortunately, at the end of the nineties a lot of negative tendencies have appeared. Many large electronics companies with decades of successful histories were split (e.g. Motorola, Siemens, Philips and others) and their successors seem to have lost most of their previous experience.

A large number of other electronics companies have started a descending evolution and, sooner or later, between 2000 and 2020, they were bought by competitors, so now only a handful of US non-fabless manufacturers of semiconductor devices have survived.

At the same time the incomprehensible fashion of requiring Non-Disclosure Agreements for getting the complete datasheets or even any datasheets has become more and more widespread.

This policy of the NDA has been conceived by morons who have not the slightest idea about how an electronics product is designed.

Whenever I design a new product, I need first to be able to read all the datasheets of all the products that might have even an extremely remote chance to be useful, to decide and select what I could use.

I will not bother to sign an NDA to learn about products that might be not useful at all for me.

The only positive effect that the NDA may have for a producer is that it might prevent the already existing customers to redesign their products, because they might not bother to obtain similar NDA from other vendors. On the other hand requesting NDA's will deter many potential new customers, especially due to the insistence on providing an estimated sales volume, before signing the NDA.

That is stupid, because before seeing the information under NDA I have no idea if I would ever want to buy 1 sample, much less 1 million pieces per year.

Managers seem much happier about NDA's than designers, because they frequently feel like they are some sort of special bond with the vendor and the information under NDA provides some sort of competitive advantage, but that is extremely far from the truth.

In most cases the only valuable information contained in the datasheets under NDA was about horrible bugs that required complex workarounds. If I had known about the bugs before the NDA, I might have never chosen those components, so maybe that was a desirable feature of the NDA for the vendor.

The end result is that when I was young and I designed anything, I could choose any component from a large number and I could easily select the best for my specific needs. Moreover, in many cases I could find a method to use in a novel way something that was not intended for my particular application, but due to the good documentation I could understand whether it would be good for different uses.

Now there is frequently just one remaining producer for any component, or if there are more of them, you might need to choose one by lottery, because without the information under NDA you cannot know who has the product more suited for you, and you can sign the NDA only if you are already committed to buy that product and not another.