Responsive web was jaw dropping when it first started but now it's become extremely common. Do people really need to do several different designs for phone, tablet, desktop?
A lot of major sites like Reddit do very well without responsive. And it wouldn't work for something like Stack Overflow because their user base are desktop people who prioritize low friction access.
It takes a long time to load and a long time to build. So most people should really rethink whether they need all this.
Websites in the 90s were slow, too. They did a lot less, but the tech was worse.
Now everything is faster but we push things to the limit and make everything slow again.
I must say that every once in a while I visit this website I made in 2007 and it's super-fast, though.