Yahoo is far worse. When they lose your mail, it's gone.
Yahoo Mail lost two of my accounts over the years. The first time was early in the service, and they seem to have lost all their accounts at once. Suddenly you couldn't log in, and there was an apology message saying that you'd need to create a new account. And that you couldn't get the same email address back, which is why my @yahoo.com address had a 2 at the end of it for several years...
Until they locked me out of it one day. As in, I checked my mail at night, then in the morning my password didn't work anymore. Since they have no human beings working for them, an entire month's worth of attempts to get access back resulted in nothing but a big pile of form letters and links to the Forgot Password page.
So no, you're mistaken. Yahoo does have this problem. If you have an account with them I'd strongly advise you to back everything up. Then switch to Gmail.
Yahoo also charges a monthly fee for access to pop3. Their web interface is slower and buggier than gmail's. There is free unlimited storage, but a smaller limit on file sizes. The virus scan on outgoing messages is usually slow; if gmail is doing virus scans, it's on the backend, it does not delay the user.
Oh, I'm on Gmail already, trust me. But thats because I like the faster interface, search capabilities, being able to check multiple mail accounts, gtalk etc. Yahoo is a great repository for my non-friends and family email (semi-spam).
I guess I've been very lucky that never happened to my Yahoo account.