Accepted by everyone as awful? No. I am putting forward my personal opinion, which happens to be shared by a number of others.
The only edition I'm going to compare it to is 3e, and that's because I'm bringing up Prestige Classes. The 3e PrCs allowed for variations and specialties in a single class (covered via subclasses in 5e) and in combining two classes into one track (mystic theurge combining wizard/cleric).
So, the multiclassing in 3e allowed for gestalt/hybrid leveling, and occasionally career changes as well, through these PrCs. Since we're using the 3e style of dip multi-classing, we need the PrCs for multi-class characters to make them work.
The only edition I'm going to compare it to is 3e, and that's because I'm bringing up Prestige Classes. The 3e PrCs allowed for variations and specialties in a single class (covered via subclasses in 5e) and in combining two classes into one track (mystic theurge combining wizard/cleric).
So, the multiclassing in 3e allowed for gestalt/hybrid leveling, and occasionally career changes as well, through these PrCs. Since we're using the 3e style of dip multi-classing, we need the PrCs for multi-class characters to make them work.