I said that Vim has built-in shortcuts for that (from what I know, Intellij doesn't) and I added custom ones because I wanted a simpler one. It's a fair point that editing a config file might seem way more complicated than modifying settings in IDE, however now that I learned about existence of config file and a command to add new key mapping, I can customize every operation I use, while in IDE I have to look for a proper setting every time.

The OP's config files are probably synced across all the servers and workstations they work with.. This is probably done using a familiar tool the OP already knew.

The IDE's config might be synced. If it is it probably uses a proprietary server.