The Brits and French wanted the P-38 asap, and the superchargers were not available when delivered to the Brits (France had fallen and its order went to England). The a/c performed poorly without it, earning the bad rep.
It was eventually used for photorecon, given the room after removing the weapon cluster.
But yes, overall, the combat deployments were fairly low in Europe. Throw in the 2x maintenance and fuel requirements, and availability of other a/c... it didn't bring anything better to the table in Europe.
The P-38's more complicated logistics requiring larger ground crews and spare parts was definitely a strike against it. However, those citing poor air performance over Europe must explain why that was the plane's fault when it had such a stellar air performance record in the Pacific including cold weather flying over the Northern Pacific from bases in Alaska and the Aleutians.
When discussing which plane was best, a crucial point often left out by P-38 detractors is that initial squadrons of P-38s send to Europe for bomber escort duty were flown by inexperienced pilots who had to tangle with Germany's best combat pilots. The P-51 came along after the cream of Germany's best fighter pilots were dead.