Yes, the risks part of a 10-K is usually pretty comprehensive, and includes all kinds of things that may or may not be an issue: that's why they're risks, and not problems or showstoppers or something. Many of the 10-Ks I've read enumerate tons of things that have a very low chance of happening.

I'd be curious about the position of these segments in the 10-Ks, like, if they're suddenly all at the top, that's much more interesting than being tacked on to the end.

I'm not sure the position is significant.

It's free to put any bad thing in the risks section of your 10-K; investors aren't going to shun your company over it. If you fail to put the risk in, the bad thing happens, and your company loses value, on the other hand, you may get sued for securities fraud - and courts have been oddly receptive to these suits.

It's like any other clause that gets added to any other mostly-boilerplate legal document over time: one firm adds it, pretty soon everyone copies their work and it's a standard term. It's viral. How fast this spreads among company filings is a matter of epidemiology, not something that actually tells you the companies' outlook.