Summoner is OP? It was considered one of the worst classes back in the day (aka when the game came out and SMN was introduced.
It's so OP that there's the meme "SMN BURN EVERYTHING!!!!" in the community.
It can give Hastega II to an entire party for 8min+. It can boost all main stats at the same time to everyone. It can use a new sort of Phalanx that nullfies what would have been lethal attacks . It can give Reraise, buff magic defense and meva (both which are very important now, since Utsusemi is useless for the most part now).
On top of that it's the top DPS for any serious endgame content. Blood Pacts do crazy damage while giving almost no TP to enemies. People just skip battle strats now, there's no point in doing them as they were supposed to be done with groups of 12-18 people. Grab 3 well geared SMN, a GEO with a mythic, a RUNE (PLD is worse now due to lack of hate management tools and less defensive magic capabilities, not to mention that an expert and properly geared RUNE can deal dmg on par with regular melees) and a COR and everything is dead within seconds skipping all mechanics because Blood Pacts still give almost no TP to mobs.
People buy Gil to buy clears from a Chinese guy who multiboxes the setup I mentioned and he can take like 3-4 people at a time charging them 80-90m Gil each for the last tier of Aeonic mobs (Aeonic is a kind of ultimate weapon that requires boss clears instead of insane grind, and it's on par with older Ultimates, and in many cases like DRG, SAM or THF is the superior option). And so Gil goes back directly to RMTs, causing a permanent inflation.
Also every item is buyable from those guys, they sell every piece of content from the game.
Frankly, it was very depressing to see the state of the game. If you try to do content with people, you're expected to be on the wheel and have all the gear bought.
I shouldn't have come back. I enjoyed the story and all but the current community has tainted my vision of the game as a whole.
SE just does maintenance and little balance updates here and there, no new content, so they don't care about the community being in shambles. Bots have someone paying subs for them too, after all.