I've found rbenv to be a great, narrow solution for a specific problem. And maybe those other tools you mention are great but I've never heard of them, so they

I've found rbenv to be a great, narrow solution for a specific problem. And maybe those other tools you mention are great but I've never heard of them, so they could use some marketing besides this comment. That's why tools like rbenv and rvm and whatever else get more broadly picked up.