It’s sort of a silly question.
To customise emacs beyond clicking around in ‘customise’ you need to write elisp. If you learn little elisp then you can only customise it using other people’s code, if you learn a lot of it then you can write an mua.
You decide where you want to be on that spectrum.
That’s silly - use-package does two things:
(imo) you’re using it wrong, I made everything defer by default then rely on autoloads and/or :bind/:commands with light use of :after . 99% of things are lazy loaded after an hour or so of work on a > 1000 line .emacs . It’s not ideal and I should probably turn most of :commands into patches upstream for auto loads but I am lazy.
emacs can be configured to use vi-style keybindings, see evil-mode. doom emacs and spacemacs do that by default, if you want a pre-done thing.
Alt key, is close to space, but it will cause me a lot of strain on fingers and cause RSI.
alt is hit with the thumb and everyone makes control be capslock or escape or whatever.
I mean, as a practical matter they are correct - most things people care about IDEs doing are just built in in other IDEs or doable via plugins. emacs is extremely niche and most people are correct to use something else.
It is an important skill to not care what other people use and not care what they think about what you use.