This is a big thing. The internet users of the late 90s just don't exist any more. The internet isn't for nerds any more, it's as ubiquitous an infrastructure as electricity or roads, everyone uses it.
The generation before slashdot from the 80s upto Eternal September were another group
You can't recreate slashdot today, because the people don't exist.
We still exist, we're just a very small slice of a much larger pie. Also, we are likely a less profitable target for advertisers so aren't an important demographic for ad-driven companies.
The other thing you mention is huge, too, of course. All the "famous" things from the 90s were basically labours of love by individual hackers who then looked for ways to fund it. Now everything is all about ad-revenue dollars.
Historically, advertisers have really loved late teens and early 20-somethings. They're starting to earn money, but don't have a lot of obligations or expenses yet, so they have a lot of discretionary income.
I also disagree that being into computers is a "common subject" these days. Everyone uses computers (some of which have keyboards), but most people aren't "into" them any more than the average commuter is into cars.
Everyone uses computers, so computer nerds are like car nerds or sport nerds.
In the 90s very few people used computers, and even fewer used networked computers outside of an office environment. Computers were new and unique.
You still get car nerds and computer nerds, but it's not the same thing when they're nerdy about a common thing.
That! Hit me hard. May be perhaps why the internet felt so different. Sigh.