Well Im not so sure that this theory is right because when itachi fought sasuke he said that if you get your brother's eyes you wont get blind so it makes no sense and kakshi got his sharingan from Obito so he shuoldn't go blind so what do u think causes the blindness
Kakashi covers up his sharingan because using it consumes too much chakra in the long run, and the acute effects of his MS is also a lot harsher than that of a normal MK. These penalties apply because he's not a true heir of the bloodline (Seeing as Itachi seemingly had no problem constantly having his sharingan activated, and has had since he killed Shisui to make use of his MK.).
There's also some rule that if you transplant any kind of sharingan, mangekyou or not into your own MS you'll gain the power of
Eternal Mangekyou Sharingan.. how that makes sense with the anatomic theory this thread is about I don't really see, but that's how it is anyway.
And to answer your question: Kakashi didn't already have sharingan, let alone Mangekyou, when Obito transplanted his eye into his empty eyesocket. And thus all he got was a ripe sharingan he could use and evolve on his own.