That's a rose-colored view that maybe reflects a small window in time.
But take the 80s. First of all that computer was maybe $5,000 in today's money. (Yes, there were some limited alternatives like the Sinclair and Commodore 64 that were cheaper.) Long distance telephone calls were expensive as were the big BBS systems like Compuserve. Any software you purchased was costly. A C compiler was hundreds of dollars. (Turbo Pascal at $50 was an innovation.)
Perhaps more to the point, most people didn't just have a computational device of any sort. So the fact that, if you had one, you could use it for a lot of different purposes is sort of irrelevant.
I'm not saying it's exactly equivalent, but there's certainly a perspective which could argue that a) the free JavaScript interpreter available on every device is more featureful and interesting than anything available to us 80s and 90s kids, b) low-cost SBCs running free open source operating systems and compilers are more accessible and better supported than the commercial compilers that few could have accessed back then, and c) the overall ramp from curious/creative gamer kid to capable hacker is much smoother now than it was then, with a lot of interim options between JavaScript and commercial environments in which to gain comfort and achieve interesting results (thinking stuff like GameMaker and RPGMaker, modding communities for existing games, hacking/homebrew/porting communities for consoles, etc).
But yeah, if the Pi shows up as part of an IOT system, or as a TV/streaming box, or to play retro games on, or whatever, then it's there and it's available to be tinkered with; and from my limited experience, basically none of those use cases will run on their own without at least a little bit of tinkering. :) Even my little Linux-running Powkiddy emulation handheld has probably consumed about as much of my tinkering time as it has my retro gaming time.
The only thing it will do is make it easier for the general public to work with machines and the masses never cared to begin with and to be frank that's a good thing. They are less likely to install malware and cause trouble for themselves.
Plus you're forgetting that these companies still need engineers to build and maintain their infrastructure so it's not like the knowledge is going to disappear, never mind the fact that the corporations heavily rely on OSS.
Great, you can write a script, it's checksum is then sent over the net and verified to not be malicious or if the service on the other side is experiencing lag..well... gotta wait, and wait.
To the point where, all choice is removed from an operating system. So much for root access.