Yeah, your business
could just accept Bitcoin and USDT
through your own non-custodial wallets for extra security,
but what if you get

Paid Often

⁠? You want to choose
with whom you share read-only access to your wallets while retaining full offline ownership of private keys. Your accountants want to keep debit and credit in sync with your bookkeeping software, with consistent currencies and rounding. Your salepeople want to issue unique addresses for each invoice and track client payments themselves. You want your teams to communicate effectively on what each fund transfer has been for.
You certainly don't have time to explain over and over: blockchains,
addresses, ERC-20/TRC-20/etc, USDT/USDC, block explorers,
confirmations, scam tokens, difference between USDT and $,
UXTO, gas price, satoshis...