Repeat it as often as you want, it still doesn't become true.
Shermans were lacking in several departments. Their armor was only adequate for the mid of the war, but completely lacking later and their gun lacked power to deal with enemy heavy armor. And even their off road performance was lacking compared to Tigers and Panthers because of their small tracks. They relied on massed charges or someone else doing the work for them. The only thing the Sherman really has going for it, is the large US economy and the stubborness to stick with the Sherman instead of continuing to develop better tank designs thanks to their "tanks do not fight tanks" strategy so that the Pershing could have rolled out faster. But winning by air superiority and massed numbers doesn't make the Sherman a good tank. If it weren't for the failing German industry the US would have been in a lot of trouble (or if they had listened to Churchill and attacked the Soviets where the weakness of Shermans would have really shown).
And your false facts about the Panther are still false.
Name another medium tank that performed better vs heavies than the Sherman then? T-34 performed worse(massive casualties), PZ IV may have been better as the 75mm was better than the Shermans one but the 76mm Shermans performed a lot better. Heavies were also obsolete either by the end of WW2 or just after it. Shermans mauled the North Koreans .
The Panther had a good gun but was mostly trash. No design feature from it was really incorporated into western (or Soviet) tank design after the war. This contrasts with German jet, submarine, and rocket technologies the Allies were only to happy to take. Read the German reports on how many tanks were in maintenance depots due to mechanical failure- that could hit 40% late war. Why did the Germans not have that problem early war with the light tanks and Czech models. Why did they use those light tanks and Czech models as the basis for late war tank destroyers. The French had Panthers post war but replaced them with American tanks as they were unsuitable for French needs (and kept breaking down).
Once upgunned how did the Sherman destroy so many superior tanks post war if it was that badly outclassed? The tank itself was good (not perfect no WW2 tank was), the 75mm was a bit under gunned vs the heaviest German armor but once again most of the time that was not an issue. There were only about 4 encounters between US tanks and Tigers on the western front. Once you get past documented actual cases of encountering German heavies most of the time the short 75mm was adequate for any target they would encounter. For the heavies they had the 90mm. The only battle of significance between Panthers and Shermans the Panthers lost as the American mobility flanked them.
Sure an 88mm would knock out a Sherman in most cases, but any other medium tank of the war would fare no better and in several cases a lot worse (T-34, several British designs). I did provide links to problems the Panther had. Most of the time (80-95%) of the time you are not encountering German AFV's and the few times you would odds are its not a Tiger or even a Panther. I also provided links to Soviet Guard units using them, the Guard units being the Soviet veteran units. Why would you give a "bad" tank to your best troops?
The other problem you had of course was no mater how thick you made armor it wasn't thick enough. Something would defeat it. Sherman sloped armor was superior to T-34 and Panzer IV + it had wet ammo racks.
Combat Footage (not a Sherman but they had things to deal with Panthers and Tigers).
https://www.youtube.com/watch?v=NBI9d0-IfEM
Even then the 76mm (Easy 8, Firefly) Shermans could deal with the German kittens (Tiger II from the front being a possible exception).
Postwar the US kept the 76mm Shermans, Israeli's upgunned them to 105mm and used them against T-34/85's, T-54/55/62 and IS-3 and post war US designs like the M-48. In Korea the Sherman's shredded the Soviet T-34/85s (better optics, stabilisers etc).