So I don't know that much about Yu Gi Oh, but I know the basic rules I think. Why is it getting banned? I looked it up and I dunno, it seems good I guess. Is searching for field spells super important or something? Aren't there a bunch of other ways to do it? I guess it destroys your opponent's if they have one, and if you destroy theirs and you don't have one then you get card advantage even though you lose advantage to make it. Is the other effect good? Do you want to skip combat to get a monster?
I don't know the specifics but it seems that it used in a couple FTKs and in a decktype that was strong in the meta, specifically SPYRALS. Not everyone seems to agree with the ban. Honestly, most of the field spells in my experience have been underwhelming, but there have been a few good ones. Ancient Fairy Dragon was probably most useful abusing field spells that gave you something when they died. Searching it up, SPYRAL Resort is a field spell that lets you search cards once per turn. Ancient Fairy Dragon let you kill a Resort, fetch another Resort, and activate that Resort for another card. It's other ability let you summon what you added for more tempo, leading to more stuff. Just what I see so far.
Field Spells in YGO tend to vary from bad to busted. While I never had much experience with the Synchro stuff, there are a lot of FS that care about getting blown up. Ordinarily, this was meant to get some value out of it if your opponent played one of many spell removers, but AFD can blow these spells up of your own volition, and you get LP for it.
also summoning additional monsters just seems to keep becoming a stupidly powerful effect
Well, in GX, there was nothing you could do with beasts you summoned. Beasts as an archetype was nonexistent. Rescue Cat probably used your normal summon, so you couldn't tribute summon, and even if you special summoned it somehow, there were better engines (Treeborn Frog.) Plus the card was impossible to search for, making it inconsistent.
What happened in the 5Ds era was that they made relevant beasts, in Airbellum since he was a tuner. So you go Cat->Airbellum+beast-> synchro summon. Another thing they added was summoner monk which made searching for cat easier. It also allowed for fun plays like playing monk, using him to find another monk, then using that monk to find cat, then using cat to summon double airbellums for two syncho summons using the airbellums and the monks. Then there was good ole Dark Strike Fighter who'd turn large tempo plays into OTKs. Two Dark Fighters on an open field could end the game. I loved 5Ds era yugioh.
Also, do people actually care about LP now? Back when I played LP didn't really matter unless it stopped you from using Divine Warning or some other card with an LP cost.
EDIT: Corrected it. Thanks.