branches are branches in svn or git... your process may not have been correct, but lets not blame the tools here..
modifying commits is a big no-no for me, so thats not a drawback at all, the fact that its not possible in svn is a win for svn.
For one of our biggest projects branches in SVN didn't work at all.
We have multiple production, test and development branches and merge branches (features) from one branch to the other (development -> testing -> production). Sometimes we cherry pick a single commit to another branch.
In those days SVN wasn't so flexibel with branches as we wanted to (or we didn't understand it enough), so our workflow was much more rigid.