There's still a lot of work in managing the custody of all that cryptocurrency safely and securely from a business perspective.

It's the same thing as a company needing a building for their factory. They decide they don't want to pay rent anymore, they're going to control their own properties they own themselves now. But the business of managing the property now falls to the business to do. So even when companies own their own properties they often end up hiring a property management company to deal the the day to day operations of running a commercial property. Because in the end they don't want to have to worry about their janitorial contracts, handling elevator certifications, landscaping contracts, maintenance techs, etc. They want to focus on producing widgets.

Same thing with hosting a digital storefront. Sure one could spend all the time managing servers on your own offices and ensure good uptime and security and what not, or you can just sign up for Shopify or others and they'll manage it all for you. If managing servers and software stacks and digital security isn't your main business competency, why get into it?

Most companies won't want to deal the logistics of handling crypto. So they'll often outsource that work, because I'm the end they want to focus on selling widgets not handling payments. For the same kinds of reasons why they'll hire a company to do cash logistics.

Do you need to hire payment processor to accept crypto? No. But in the end you will need to do that work though.

I'm not the reason why people choose these big centralized services. I'm not that powerful. They choose them because they see value in the services they offer. Not everyone wants to be their own bank.