and doesn't mention that they are a C programmer or anything. It is extremely unlikely that OP
can customize the entire things by modifying the source code
because it is extremely unlikely they would have any idea as to how to do such a thing. How many people, on earth, in total, can set up, run, and edit the source file of a tiling window manager? Now remove from that value those who are existing linux users. Functionally 0%.
This person wants to start using linux, is asking very simple questions. They are asking here which suggests they do not have a deep and rich existing network of people in their life to provide 1-on-1 support. Otherwise they'd ask one of their many sysadmin friends for individualized advice. You are suggesting to them something which takes a pretty wide diversity of skills and knowledge. And since the specific thing you are suggesting is a window manager, when they can't figure out how to use it, they will be unable to use their computer.
I wouldn't advise a beginner start with vim on day 1, but at least if they did they'd still be able to use the computer for things other than text editing. And find a different text editor while they learned vim.
This is stunningly bad advice, verging on sabotage. Why do you want people to hate linux?
Sucuk