Well a simswap attack requires the account password, since otherwise you would not be able to receive an SMS message for the two factor part.
But without two factor, only your account credentials are needed.
So yeah, it's definitely better than nothing, you are effectively forcing your opponent to social engineer your carrier, and doing that generally requires knowing the full number and usually at least your name, if not more identifying information that's harder to get, like social security number or equivalent.
Sure, TOTP or other two factor mechanisms are better because they require access to one of your authenticated devices (assuming the TOTP isn't done by a secure enclave), but SMS two factor is definitely better than disabling two factor.