Plus equal work porting/valve/vj etc.. to 360/5.9 heads will give you probably at least 40 more cfm over 273/318 heads why give up 60+ hp, nevermind a set of aftermarket heads.
No one is saying 302 can't work, they just don't make much sense in most cases.
Imagine a basic zero decked 318-328 with a xe268h cam airgap and headers. Now picture it with everything from stock 302 to edelbrocks maybe even trick flows and the power differences.