Why doesn't EA ban paid modifications?
Well, first, i have played many games with mods, where modding community's core is just enthusiasts who love the game and want to make it better, and want nothing for the mods they are creating, even if they spent years developing, i often donating to ones i like most.
But the EAFC/FIFA modding community is built different, i have never seen such thing in other games. Im talking about relatively big mods with some amount of content - there are no enthusiasts, their main goal is to make money, so they are hide the mods behind mandatory paid subscriptions on patreon (or similar platforms). Some of them who less greedy and more responsible keeping the price under $10/month and using something like "early access" destribution model (paid subscribers get access to latest updates immedately, and then after few days they post it for free), which kinda okaaay.. (but concidering that with game Title Updates(TU) most of mods became unplayable, and how often TUs releasing by EA - you have to get paid subscription if you want to continue to play your save and not wait for 5-10 days for free release).
But there are another level greedy modders who put crazy $20-$30/month price tag on subscription, adding activation via patreon and not posting it to free access (or doing it once per 3-4 months, which is nothing cuz it got bricked with next TU after a week or two, just dust in the eyes). In my opinion, this kind of mods and modders should not exists. And people should stop encourage them by bying that scazy subscriptions. Wanna support modder? Just donate, and you should if you like it and if you have ability. But it should be on free will and not mandatory.
And it worth to mention, the main reason why this kind of modding community are built - the lack of content and features in offline mods of the base game.