Earlier quoted context omitted.
I hate to think what it would mean to be dependent on SO. I think overall we are agreeing. USENET and various sites were a huge jump from the state of things before hand, when your available resources really depended on location. SO is a more useful interface on top of that stuff and easier to access, but the real innovation was made decades earlier.
Yes, though the "cat is out of the bag" now with SO, so it could be replaced if/when it falters. The next version might implement a versioning strategy, say questions/answers get archived every five years or so.
Before that, you'd get books out of the library and get a pad of paper and hand-assemble 6502 code and read Byte magazine and if it took a long time, you learned it very very solidly. So I'd say I got a level of deep understanding from hand-assembling code for 6502 that I (as a fogey) doubt I would ever get from any amount of SO reading. Tho my general work flow once I start typing is to google every thing that I can't instantly fix; weird compiler error, cut and paste into search bar, optionally add "stack" to the end and read.