Correct. To be specific, instead of providing a unique address per deposit, Coinbase instead provides one address, and identifies individual deposits to that ad

Correct. To be specific, instead of providing a unique address per deposit, Coinbase instead provides one address, and identifies individual deposits to that address using a Stellar "memo." The same issue is present with Ripple. This isn't a problem with Stellar itself, but more how Coinbase decides to approach the issue. But Stellar does require a 0.5 XLM commitment to "open" an account on-chain, which is probably what holds Coinbase back. Otherwise, Stellar is a very reliable and focused chain, and has a stable fee market (which means a lot these days!).