I'm sure there is a logical reason for the 150 card limit, but for the life of me I can't see it.
If someone what's to hold 800 cards, let them. It doesn't effect the gameplay or give anyone any advantages.
I guess the only thing I can think of is it forces people to clear up the cards and not keep a bunch of " I might just need them in the future " cards.
I know I'm probably missing something......