If Amex Plat gives Bonvoy status, is there any point in getting a Bonvoy card?

Been using my Amex Platinum for a while and realized I already get Marriott Bonvoy Gold through it. So what’s the reason people still sign up for the Bonvoy credit cards?

I usually just charge stays to my Amex or Chase cards not super deep into points strategy but wondering if I’m missing an actual benefit here.