After this thread became a discussion of competing, sometimes extreme approaches, I want to add one alternative. Markdown files, organized in folder hierarchy and synchronized by the service of choice are fine for me - for notes and knowledge collection. Recently I started to add the superpower of tags and links to other files by using Apps like Obsidian[1] and Zettlr[2] which are very similar. The great advantage is, that you just show these apps the par of your notes folder and are not maintaining notes in an app-specific environment. The syntax for tags and links is simple and will not disturb massively even if opening the files in a text editor.
This approach merges the simplicity of plain text, the power of tags and links and keep this independent of the of synchronization, backup or future development of these apps or anything in this stack of tools.