That's usually a good thing, setting your HEAD to a symbolic ref or a commit are very different operations. Having a switch makes sense and probably catches beginner errors rather than letting them know afterwards.
I don't feel like typing 'git s -d <branch>' has slowed me down in practice but you're technically right of course (or I would add a 'd="switch -d'"' alias).
I do see a point though. Ostensibly, sure, it's hard to be so confident that a program does not have a certain feature that you can deny it without looking.
But think about this case. Would it make sense for git switch to have a delete option? Of course not. But you can't be sure, because, git. The feeling is that they would merge something like that.