Once your YT account is removed by YouTube, how do they stop you from making other accounts? All a user has to do is open their incognito tab on their device, make a new address & make another acc with that tab.

They block your MAC address or your ISP address those aren't covered by "incognito mode".

Incognito Mode just blocks cookies and clears the history for your own computer, and is meant for privacy when someone else uses the browser on your account. (ie. A family member "borrows" the computer and you didn't out log out first.) It doesn't effect what information websites get from you. You would have to use a proxy.

If you're just talking about an account you use to view and bookmark stuff, you can easily get around that with a VPN.

If you're hoping to make money from your channel or something though, you'll have to start giving them personal information - and you're kind of stuck at that point unless you've gone to a lot of effort.

Google can black list your IP address meaning any accounts that uses that IP will be terminated, but if you use a VPN service it really doesn’t matter.