And then it was discovered that it is effective tactic to make money. You could sell all cards in the set for 50 or alternatively you could sell bunch of packs mostly filled with filler for 150 and get people buy quite lot of them to chase the limited set of strong and competitive cards.
It absolutely is and it absolutely should be. Secondary market is very real and some cards in certain products are expensive there. Something like the "The One Ring" one out of one unique card in MTG is clearly a type of lottery. That card had expected secondary market value in hundreds of thousands if not millions.
To me if we are going to regulate loot boxes, trading cards should be regulated as well. Or at least minors should be banned from buying them.