On the frontend, you have build pipelines, bundlers, CSS frameworks with their own toolchains, progressive web apps, Core Web Vitals, SEO, layout shifts, srcset/responsive images…I've been making web stuff for a similar length of time as Mattias by the sounds of it. I started with Perl but moved to PHP 4 pretty soon after. I recognise this problem but I have different take.
All the complexity was there 20 years ago, but we ignored it. That doesn't mean it was simpler. It just means we took crazy (with hindsight) risks. Sure, there were no build pipelines like today, but we had scripts we ran to build things. There was Adobe Pagemill for making site wide changes before we deployed a new version. Back in the day we made those changes, did a very brief check that things worked locally, and then manually FTP'd files to a server, breaking it in the process because a user would see the site change as they navigated. Some of us would put up a maintenance page during an update effectively just blocking all the traffic. That's certainly 'simpler', but it's also much worse for the user, and on a site that did things with data potentially risked corrupting a user's records. It was incredible that things didn't break more often. Maybe they did and we just never realised.
We didn't have CSS frameworks but we certainly did have our own in-house templates, and they had separate toolchains. As time went on that toolchain mostly migrated to Wordpress and it's template builder plugins. Again, give me Tailwind over that mess.
We had Core Web Vitals and SEO in the form of Urchin Stats. We had layout shift but we called it FOUC. We had kind of had srcset, but it was implemented as a set of Macromedia Dreamweaver mm_ JS image preload and swapping functions. is a lot nicer.
Things are just better now. Writing web software is loads of fun. I also leverage LLMs in my code because they're awesome, but not to simplify things. I don't think the complexity is new. I just think it's visible now.