Why would knowing if you randomly solved some blocks help you decide if you should mine solo? If you just want an estimate it's a pretty obvious calculation to begin with. Just see how much you earned in BTC, add back their fee, and divide by 50. That's how many blocks you would have solved on average by solo mining.
You obviously don't understand bitcoin. I already know what my average Bitcoin solving rate should be but... Bitcoin involves a large amount of variance, people are happily hashing away and they might find a block in 5 seconds, or they might never find a block. The reason we mine on pools is that we don't want to deal with that variance. Pools incentivize people by paying them to hash for them even when they don't actually solve a single block.
So, finding statistics about how many blocks I've actually solved gives me a little history on how lucky a fellow I am. Thus far I'm a very unlucky fellow. And if that trend continues staying on a pool is the most reasonable course of action. If I missed something and I solved a buncha blocks without knowing it, that gives me the confidence to say I could potentially go solo.