Except before they changed the front page it wasn't like that at all.
The fact is "raw" Reddit is nothing to write home about and the previous front page worked around that with default subs.
I have no idea how it makes sense from a user conversion perspective, since new visitors essentially see the crappiest sides of Reddit before they even make an account to then go and learn how to filter it. I know personally if the first time I visited Reddit I saw what I usually see on the front page these days I probably would stay accountless