After all any aircraft is better than no aircraft.
They did - Germany with 110’s in BoB, USA with P-38’s in 1943 - both were relative failures.
Because they were not as good as single engined fighters.
Note that he main reason for hte Pe-3 was the lack of NIGHT fighter in the USSR - multi-crew night fighters were useful due to teh technology of hte time, endurance and lack of single-engine opponents.
Night and bad weather fighting remained the preserve of large multi-engine fighters for quite some time after WW2 due to the large size and power requirements of radar required.
Not sure why you think it sluggish, unless it you’re referring to the berlin one which I haven’t tried yet, otherwise Moscow IL2 to me is quite maneuverable.
idk man take the berlin (ah shit i forgot what it call) attacker 2 for example it super fast but when it turn it feel super slow it something like that but for IL2 it like all slow to me cant explain it
“Heavy fighters” were often used very differently by different countries, so unless you mean “interceptors” it’s a bit of an odd category, and even then most had success in some respect. To go through a few examples:
Bf-110 was classified as “zerstorer,” which as I understand was originally intended for use as a swing role, across a very large number of roles. As a result, one of it’s intended uses as a day fighter struggled. As the Germans narrowed down its role, it still had a great deal of success as an attack aircraft and particularly as a nightfighter, founding the basis for the 410 when the technology matured.
P-38 seems to be a favorite here, so I will leave that to others.
Beaufighter was based on the success stories of Beauforts getting caught in unintended engagements and capitalized on promise they didn’t know the Beaufort had shooting down other bombers and sometimes fighters. After narrowing down its role, it was highly effective at ASW.
As for the subject of the discussion, I am not as familiar with the Pe-3 so pardon me if I get a few things wrong, but my understanding is that while it was used for CAS, it was mostly used for interdiction of both bombers and ground units, the latter being more successful. My understanding is that it was more successful in interdiction than CAS, due to its speed and range (which I need to check up on its range for sure).
Anyway, you get the idea. The dedicated interceptor was largely an emergency use aircraft where if bombers are not shot down, there won’t be much point landing anyway. It was also mostly developed out of the interwar at a point when bombers were much faster than fighters for a limited time.
I should add that until the late war, there was at least one party that did practice sending heavy bombers against a target unescorted. In these cases, interceptors (including the “heavy fighters” mentioned) are more efficient at shooting down a large number of bombers quickly than aircraft oriented around air superiority (such as the Zero).