So you are saying every arcetype should be viable and every deck type should be viable?
Don't try to straw man me here. Archeops was a problem because any deck could splash Archeops + Maxie's pretty easily meaning decks using evolutions had few decks it could actually be played against because every deck could just tech a card that turns your deck off. As a result there was no point in even considering evolutions as a deck
Ghetsis in this perspective is not as extreme as Archeops is but there are decks that are very item heavy because that's how the deck works (like Night March, Rotom Box, etc.) and would run into basically the same issue. If i choose to play a deck who's whole point is being item heavy and my opponent splashes ghetsis then I have a very low chance of winning just because my opponent teched a card that can be ran in every deck without issue.
Safe Guard and Imtidating Mane aren't like this at all. They aren't easily splashed into ever deck, it's very easy to tech cards that can deal with them, and there are even ways to deal with them outside of teching (such as just gusting around it).
And this is still on top of the fact that even if everyone does play lower item counts, every deck still plays items so every deck still has a chance of randomly having a hand that can get Ghetsis'ed and lose instantly