well with this logic, if you could block with duel wield
WHY WOULD YOU EVER USE A SHIELD OR A 2H WEAPON!!!!!!
Because two handed weapons have perks that let them do disarming, disorienting, and area of effect attacks and generally do more damage, and
shields can bash, deflect much more damage, offer armor rating, and are incredible crowd control tools because enemies that attack you when you block get staggered, giving you free hits.
Blocking with a weapon has always blocked less than with a shield. 2h versus 1h and shield makes sense, two handers do more damage and are more offensive but they can still block, just not as much as with a shield.
In fact, 2h versus 1h and shield is EXACTLY what dual wielding versus 1h + shield should be like.
2handers should sacrifice defense for slow but powerful strikes, but they can still block already.
1h + shield sacrifices offense for more powerful defense and a bit of crowd control.
Dual wielding melees should sacrifice defense for faster strikes (but not more powerful ones, dual wielding does not make you more powerful, it makes you faster.) But just like wielding a two hander, you should still be able to block, just less effectively than with a shield.
So by your logic, tell me fools, how is it fair that two handed weapons can block when they have a high offense?