The number of religions depends on how you define it. When you get into the thousands you are talking denominations more than religions. And while there are tens of thousands of Protestant denominations on paper, the significant differences between them are such that a few dozen is a more realistic number. People regularly move between, e.g., various Baptist denominations (American, Southern, etc) and between those and other evangelical denominations -- for no other reason that that they moved or don't like the new pastor at the old church. It is no more consequential than choosing a different brand of bread or milk. Differences in texture, packaging, appearance, and flavor doesn't make it follow that there are thousands of brands of bread means it's some sort of indictment of bread.

The real problem with religion is religious faith, which is a failed epistemology, no matter exactly how it is delivered.