It makes no sense to redefine the Magic term; it just leaves you communicating poorly with Magic players, all so that you can say something dull about Ruined Market or whatever. You get zilch out of it other than communicating poorly; zilch I say.
"Strictly better" is when one card is always better than another, ignoring stuff like "what if I take control of your thing, now you want the worse thing." In Magic, strictly better/worse cards appear in most sets. In Dominion, I don't make them. Magic initially had some, for a while tried to avoid them, then gave up as it was impossible and hurting the sets. Dominion has a tiny fraction of the cards and isn't trying to sell people stuff they already have.
If you want to talk about how one Dominion card is better than another, say "better" and you will do a better job of communicating.
Now Dominion does have printed cards that are strictly better than others, just going by the printed wording; for example 2E Throne Room is strictly better than 1E. However the idea is that you play the 1E version as the 2E version, leaving them the same.