Agreed!

I first started using Emacs in 2015 or so, sometimes still relying on other editors (usually IDEs) alongside it.

I was still in school then. By then, I'd used for varying lengths of time (and had been taught, to varying degrees): DrScheme, BlueJ, Visual Studio, Eclipse, NetBeans, and IntelliJ IDEA. (I'd also used vim, Kate, and Notepad++, but I used those mostly for editing configuration files, plaintext notes, and shell/batch scripts. Vim was the only non-IDE editor I'd ever used for any real programming, which amounted to my coursework for a few classes in college.)

I didn't dive in with writing my own config from scratch, but started with Spacemacs as someone with prior (and merely casual) vim experience. It was better in some ways and worse in others than those 'modern' IDEs I'd used previously. Performance was worse (although resource usage was much better) in that sometimes Emacs would hang or pause for slow operations. Startup time was slow, but client/daemon support made that invisible. The total stack I ran was noticeably buggier than alternatives like JetBrains, because a distro like Spacemacs glues a ton of external packages together. Spacemacs releases were infrequent so I ran against development branch, inviting more bugs.

But the main thing that struck me was how nothing else I'd ever used was as easy to learn as Emacs. I loved all the search-driven workflows and interfaces, how fuzzy-filtering was everywhere. I loved how running commands 'manually' always showed and reminded me what their keybindings were. I found myself learning many more keybindings than I ever did with other editors/IDEs, because they were so easy to look up, and looking for many more 'interactive functions' (commands) than I ever had before, because they were so easy to search. It had quirks, and I was grateful to have a 'starter kit' in Spacemacs (without which I likely never would have picked it up). But overall it was clearly, decisively better than anything I'd ever used in virtue of its radical discoverability alone, and I quickly built up muscle-memory for the Spacemacs bindings.

Automated refactoring and advanced code navigation were clear weaknesses, though. That's why I sometimes used JetBrains IDEs for some languages in the years immediately following.

Nowadays I'd say things look even better for Emacs as compared fo IDEs. It has pretty good performance, and more and more packages do things asynchronously where it makes sense. Virtually every programming language has one or more LSP implementations, so good code navigation functionality is easy to come by and old tools like etags can still be used as seamless fallbacks. (I don't do much work in static languages lately so idk how good the refactoring support for popular LSP implementations really gets, but basic refactoring in Python seems fine.) Emacs even gets along well with the new 'AI' hotness; its documentation culture and fine vintage mean that ChatGPT and friends are better at writing and explaining Emacs Lisp than the vast majority of programming languages, plus they 'know' lots about not only Emacs built-ins and popular packages, but even the configuration idioms and special macros of popular Emacs distributions like Spacemacs and Doom Emacs.

I no longer use any other IDEs anymore because I don't see any reason to for my current use cases, though I do still use Vim a little. Recently, I've started occasionally using VSCode to test things on behalf of my users at work, who are other developers. Far from decaying or falling behind, I think Emacs has become a steadily more attractive alternative to IDEs since I started using it. I don't begrudge anyone their VSCode or JetBrains IDE if that's what they've already chosen, but I'd still recommend Emacs (with a good starter kit) over either to programming novices today.