I'd say we're likely comparing apples to oranges here. It's a common complaint on HN that frontend development is a mess and evolves too quickly, that it isn't "what it used to be". Static pages, small downloads, very little coding overall. What we miss is those kind of sites still exist, but they're not the sites we're complaining about.
Back in the late 90's and early 00's, most websites were largely "brochure" websites. Companies were getting online because they heard about this whole internet thing and they knew they just needed to "get on the internet". You largely saw companies uploading whatever brochure they had basically into a digital one online. Those websites were insanely straightforward. Render a page, static content, the end. Maybe it's a little more dynamic than that, perhaps you're running a basic LAMP stack listing, say, real estate. Query the database, render the page, we're done here. Very little interactivity.
Those websites still exist, but they're likely not the ones we're complaining about. Site's like boeing.com are those traditional brochure sites which deliver very little interactivity. Relatively quick and nimble, the hero image is larger than all the JS they load (and, honestly, they could probably remove most of their JS now - they're using jQuery, modernizer, underscore, stickyMenu, require.js and a bunch of probably unnecessary jquery plugins we can eschew today, but we're here to complain about today, not praise it amirite?).
What we're actually complaining about are usually the interactive sites. Your Twitters, Facebooks, even sites like Reddit that dynamically load content as you scroll, click posts and download more content, comment - all manner of interactivity. Typescript? React? Functional components? Hooks now? Learn Redux? Unlearn Redux? CSS flexbox? CSS grids? My website now has a build process? I used to just edit the PHP file and upload it via FTP. What the hell?
These are not simple "brochure" websites, so yeah, they're more complex. They're applications. And being that they're applications, we shouldn't be comparing them to brochure websites, since they're delivering a completely different experience and have a completely different goal. We should be comparing them to desktop applications and the desktop application development environment, and therefore, comparing their stacks against the likes of C# and WPF, Swift and Cocoa, C++ and Qt or C and GTK.
And compared to those tools, how does the modern web development tool chain stand up? I have no idea, I don't write desktop applications! But what I do know is companies like Slack and Discord have elected to use electron rather than create their products in whatever desktop application framework. VS Code is electron-based and being a Microsoft product they had all the reason in the world not to do that - and it's dominating it is space today. Offerings like Figma, which by all rights one would imagine should have been desktop software elected to be an online tool and has completely shut out the competition.
So if you're going to complain about online applications, don't compare it against an old programming paradigm that would never apply to these products. Compare them against the modern desktop application development experience and let's start the conversation there.