Yeah, that does sometimes occur to me when I think about it. But there are plenty of things you can have instead of meat: in fact, part of the problem is that so many foods we're accustomed to having with meat. I had a mushroom lasange that tasted wonderful, and they say pulled jackfruit is better than pulled pork.
Although...being vegatarian would be difficult if you had certain religious or cultural foods that always contained meat, or if you had an iron deficiency.