Ruling for Thirst for Knowledge?

[computer]

according to the text on Thirst for Knowledge, you can either discard two cards, or discard one artifact card

But the ruling in gatherer says that you can discard two artifact cards "if you really want to"? since when can you do something not listed in card just because you want to?

[Arix]

It is listed on the card - it says you can discard two cards. If you discard two artifacts, then you've discarded two cards, thus following the instructions written on the card.

[Kenji]

Notably, Thirst for Knowledge doesn't say "discard two non-artifact cards unless you discard an artifact card." If that was the intention, then it would've been worded that way. Since it isn't, you're certainly free to discard two artifact cards instead of just one artifact card. It's not usually advantageous, but it's certainly possible to do anyway.