You’re spot on.
Do you know why? Because it’s the logical answer.
It’d be great if Blizzard could allocate the resources to create a parallel single player experience for those that don’t want to or can’t group with others, for whatever reason, but it’s not reasonable to ask that of them as if they owed it to you.
There’s plenty of Single Player games, or even MMOs that are more geared towards the casual audience.
Blizzard can’t provide a life to those that have no desire to seek one outside of WoW, such as yourself, or even the OP.
Let go bro. There’s a world outside.