You could, but then you will have to continuously monitor the main branch and pull in updates if you want new features, bug fixes, security updates etc., and po

You could, but then you will have to continuously monitor the main branch and pull in updates if you want new features, bug fixes, security updates etc., and possibly you'll need to deal with merge conflicts. You might also need custom release, install, and upgrade tooling for your fork. And if there are bugs in anything that has diverged, it will be up to you to fix those yourself. It's significant extra work, in short.