I wouldn't say MBA is the bottom of the barrel, but the school matters. Certain MBA programs will definitely open doors for a lot of people, but those opportunities drop off sharply after the top10/15 and even more after the top 25/30. It's not to say you can't have good outcomes, but your expectations should be tailored accordingly.
It's not easy getting into the top schools, but it is certainly easier than getting into their respective undergrads. The problem with a lot of MBA programs is that there is non-grade disclosure and it is pretty difficult to fail, so a lot of student's don't put in the effort, but that's not to say you can't learn a lot if you make it a priority. You get in what you put out and the teaching faculty and school resources are all top notch. Generally speaking though, at a top school, everyone generally has some base level of intelligence.
Now the other master programs, even at top schools, can be super cash grabs. Often times, from my anecdotal experience, is that it is all full of foreign students, especially Chinese, who are paying full sticker price for some cash grab masters, so that they can put some school with brand prestige on their resume.