Wow, yeah that domain must have cost a ton of money. Wouldn't that be worth at least 5 figures, maybe even 6? Is that something that YC would encourage them to do, and maybe help fund the domain purchase?
You're right, the domain wasn't cheap, but we had it prior to YC. We bought Solve.com at my last company (n/k/a StudentBrands.com) for a math-related product we were going to build, but we decided to focus elsewhere and didn't use the domain. Anyway, we were able to work out a way to use it in a way that worked out for everyone.
I kind of expected something like that, based on the generic-ness of the domain. Hopefully you can leverage that generic-ness into solving other problems under the same name.
Definitely something YC encourages (.com domains), but definitely NOT something they would encourage you spend YC money on. They would tell you to pick another domain, like getsolve.com or something.