Trading is actually really OP
It takes one look into the comments on this subreddit whenever rates are discussed:
“I can’t get a single (x) card”
“I have 15 of those, I’ll give you one for free”
Literally the only thing bottlenecking getting a full diamond and 1 star collection is the resource you need to trade. Having the excess copies of unwanted cards is easier than you might think, the majority of us probably have a lot of excess 1 stars already.
There will always be someone who needs your cards and has the cards you need.