While I would agree with the sentiment that Michael was a stronger all-round driver than Lewis is overall, you can't really compare pure results like that in F1, because it really depends on what car you are driving, how good your teammate is, whether you are getting preferential treatment or not, etc.

It's no surprise Hamilton never got more than 5 wins in a season in the V8 era, because arguably he never had the best car over the course of the season. The 2008 car was probably the best car he had driven before 2014, and even then it was most likely behind the Ferrari. Meanwhile, Schumacher had many dominant cars at Ferrari, along with an average teammate and preferential treatment. There's no way you could reasonably compare the two situations.

Personally, I rate Schumacher as being almost certainly within the top 3 F1 drivers of all time, possibly the best if you are only counting the downforce era. But I actually rate Alonso as being roughly on par with him at their respective bests (I know it's a controversial opinion, but looking at the teammate stats there's a strong case for it). Did Alonso ever completely dominate a season like Schuamcher did? Not really, but that's no reason to say that he's not as good as Schumacher -- he just never had a dominant car. His performances in cars that were the 2nd, 3rd, 4th, etc. best were still mind-blowing in certain years.