In 5e I can take a level of warlock and at character level 5 the cantrip outdamages a heavy crossbow.
I can make a warlock 2 / bard 3 and both of their selected cantrips scale based on Character level.
You should absolutely be able to mix and match extra attack features. There isn’t a reason, other than 3+ attacks is a primary fighter feature, that extra attacks shouldn’t stack.
Why is it insane though?
In 5e I can take a level of warlock and at character level 5 the cantrip outdamages a heavy crossbow.
I can make a warlock 2 / bard 3 and both of their selected cantrips scale based on Character level.
You should absolutely be able to mix and match extra attack features. There isn’t a reason, other than 3+ attacks is a primary fighter feature, that extra attacks shouldn’t stack.