I still have the cards, they have a resale value. More than I spent on the game, as some have become difficult to find. Of course, this could change (I don't really think they'll become worthless because MtG is not just any CCG, it's quite iconic due to its history, but it could happen), but at the very least they are a physical item that remains there and can be played with. When my son grows, he will probably enjoy them, regardless of their value.
Loot boxes for games that give you a virtual item that you can't even sell or gift and will probably be worthless in 4 years when the server closes... now that's a scam, unless in exceptional cases (small one-time purchase to support devs, etc.). I don't spend money on that and I wouldn't let my kid either.
The thing missing from these virtual items are a framework to ensure they can actually carry value.
And that could be NFTs or something similar. It makes sense to me, even if some of the “valuable” assets so far do not.
But then again what does my almost-tournament winning goblin grenade deck mean to a roblox player now? Presumably, little.