There are many things to address here.

• There's no such thing as hoarding cards from other player in Terraforming Mars. All players get the same amount of cards each generation and there is nothing you can to do prevent your opponent from getting them.
• You can purposely not play cards that terraform (especially with the CE variant) to stall the game, but this doesn't stop your opponent from using their own cards or even the generic projects printed on the board. If you see your opponent is stalling in TM, you should double down on terraforming projects. Not only will you pick up VP that they aren't, but you'll undercut their free points engine. *If you really must know, I'm downvoting you for complaining about off-topic subjects, like downvotes and redditquette. Downvotes are irrelevant to OP's questions.
• If you're that cheesed about downvoting, why are you downvoting my own posts before replying to them? We can sit here and downvote each other all day if you'd like, but it seems you're a pot calling the kettle black at this point.