Thats true they didnt win every T1, but what i am saying is the team with the most likelihood to win is Astralis. There wouldnt be any logical reason to pick another team ATM. Some might say stuff like; if EG come back to where they were then they can win the major, because they have beaten Astralis in the past. I dont think that makes sense, but ok.
Also, majors are just prestigious. And if teams want to make history they want to win the big one. So id say they arent overrated, but there have been shit ones in the past (faceit). I doubt Astralis would allow anyone to win/ take a major from them. However, there are T1 tournaments that are sometimes better than majors such as ESL one Cologne, Katowitze and perhaps a couple more.
Personally, I have a feeling that Astralis wont win the next major and i cannot explain why i believe so. Then again I thought TL was going to win the previous one. So maybe my gut feeling is wrong, and most likely is.