So again, are there any specific advantages in everyday work for ordinary user or it's more convenient for people who need to idk, monitor lots of things at the same time without overlapping windows?
In my experience with tiling, almost everything is faster. It boils down to vim vs a mouse based editor. People prefer it because your hands already on the keyboard, why move them to do arbitrary things like window switching?
Example: your web browser is always accessible with Win+2, the window to the left is Win+h, your terminal is Win+Enter, etc. It's trivial to create a binding for something you do often, for example press Win+q to create a QR code from your clipboard. If you don’t like any of those, it's easy to change them to fit your style.
Also it seems like you aren't consnidering workspaces, which are key with tiling window managers. If you had only one workspace then yeah, just having 4 windows would already cut your window size. Workspaces allow you to have multiple desktops of tiling windows. So you could have just one window in workspace 2 and 4 windows in workspace 1, ...
also no more window title bars meaning more screen state and a cleaner interface