On the importance of using what's already in Emacs

One of my biggest pet peeves is people not understanding and making use of all of the powerful functionality that Emacs already provides. (That's why I created Quake Emacs). So many packages have been integrated into Emacs's core, and Emacs itself has been extended with so many incredibly powerful features over the forty years of its evolution, and yet so many of them are poorly documented or marketed, off by default, or badly configured out of the box, that oftentimes people prefer to use huge overhaul packages that complete reinvent the wheel, replicating functionality that could be had with core packages.

What's the actual problem with this besides just wasted potential, though?

In my opinion, it's really two things: one, these big reinvent-the-wheel packages usually require a lot more maintenance than they would if people built on the shoulders of giants, configuring, or improving what's already a part of Emacs, since these packages typically have to reimplement the built in functionality and then go to extra effort to integrate with Emacs on top of it, when all that effort could go into improving the stuff that's already being built and maintained in core Emacs, and two, those big overhaul packages usually don't integrate as well with core Emacs and other packages, possibly also requiring any packages that want to hook into their new more advanced functionality, rather than the functionality that's on by default in Emacs, to explicitly depend on these packages, which makes the Emacs ecosystem a lot more brittle and less modular and composable.

However, there is a new breed of overhaul packages that at least don't fall foul of the second issue, like Vertico and orderless.