If these are the Aeon weaknesses, it contains three of their strengths.
The destro is still the 2nd best destro, of course it’s worse than the best destro but both salem and valiant suck against exodus.
Harbs are absolutely not just good early on, they are the overall highest utility t3 land unit and are good across the entire t3-t4 stage. They are great at drops, at raids, at small number attacks, and at large number attacks. The only unit arguably as useful as harb is brick since it got buffed to just be a strictly better percy, putting percy over harb is completely nuts and not based in reality. Percy is like the 3rd best t3 unit for UEF let alone a unit to put into an argument on strong t3 units.
GCs are the perfect complement to harbs. Harbs suffer late game from not being able to force engagements due to range. A GC not only provides excellent HP tanking but it also forces essentially anything that isn’t a mega/fatboy into a fight when supported by either harbs or potentially snipers. Talking about GC dps just sounds like you aren’t using GCs properly nor do you understand what purpose it serves alongside harbs. You thinking this is how you use it just goes to show how strong it is, because you can just meathead spam GCs and still get completely solid results.
Czars are just really big restos, you’re not supposed to just fly over sams and have it die. I'll admit it isn't a strength tho.