Because they're beyond popular among all of the high ranked players

Shakra is brutal.
Ratanah could see an unbanning, maybe.
Lou 2hKOs with like every Roots menber furied, not to mention the +att ability.
Yookie is like 3* Yayoi.
Kiki Cr, well...
Arno's ban was made to weaken
Roots.
And i think that's it. 6 good cards with fair replacements.

Soa is great in elo. As you play more you'll understand that taking away the ability of a deck takes away all the synergy of a deck. Roots are still good with all the cards banned

They are badly hurt by the bans but I think its because the UR team has realized how strong Roots and SOA as a bonus were. They still have quite a few strong cards though.
2*: Treeman & Flora (arguably Jeto & Miken Moose)
3*: Noodile Cr, Rico, Gertjan, & Jeena (arguably Ellie)
4*: Gretchen & Tuck (arguably Armanie & Burdock)
5*: Now this is where they're weak. Ojibway is considered usable by some but I personally don't like his lack of round winning potential and lack of versatility. Rosen may be another option but she is not really anything special.
Overall still a quite viable clan but not as OP as before.

SoA is SICK in elo. currently, im still using a mono Roots deck to great success (mainly because of Uranus). all of their cards DESERVE the ban, and they have great great replacements.

Ratanah... no shes forever on the ban list. the only 1 i can see is maybe Lou, but i dont see the point because Ojibway is very threatening. @turtles Ojibway is very usable, just dont use him first turn then its a coin flip. bait with something like Treeman, then send in Ojibway round 2 OR 3. 10 damage for SoA clan is insane.

Amanie and Ellie are great round changers as mentioned. Miken Moose burns pills. another card that is quite viable but never seen is Armand. at SoA weeks he can be quite doable. basically if Gertjan is unbanned Roots dominate the week.

Ojibway = Lou that can almost never KO. This makes Lou >>>> Oji, IMO, at least...

Even with the bans Roots is still one of the strongest clans in elo mode, as for why they are always getting bans its because they are simply to versatile as a clan without the bans. Shakra and Lou are solid high damage cards that are trouble to deal with due to soa, Ratanah is an above average 4 star with attack manipulation and soa, Arno is a DR immune to soa that isnt Roots/GHEIST. Yookie got banned because having 3 3* cards that are some of the best made Roots half decks too strong. Roots has always been a clan that is extremely powerful with low star count, when most of the staple Roots cards are 3 or fewer stars its really scary how efficient of a clan they are. They have their stronger 4 and 5 star cards ban to prevent them from being strong in every way, without a reliable nuke they at least have some weakness.