It was okay when it came out because the alternative was EDLIN (DOS version of ed). But IIRC, it had a 64KB file size limitation which was a problem.
There were loads of native PC text editors, too. SemWare's QEdit had been around since 1985, for example. DR-DOS had had EDITOR for a while, which might indeed have spurred Microsoft into action.
Boxer was a contemporary with MS-DOS EDIT, but that name was a pun on the name of an earlier widespread DOS text editor named Brief, also around for years before EDIT came along.