I agree with almost everything, and obviously its not as simple
But the myth that prime Connor was invincible, was obviously, just a myth.
He had submission losses to Sitenkov and Duffy, so his lack of ground game was known, and the Diaz fight also expose his lack of cardio (or incapacity for pacing) and low fight IQ (or incapacity for a plan B when the left isn't ko'ing your opponent).
This is MMA, so unless he was able to be extremely serious in his ground game training, he would always be vulnerable to the better fighters at 155.
At 145, his left hand was able to cover for those gaps in his skillset, as he could shut down everyone, but at 155, he would always need to become a full MMA fighter to have any chance to beat the top 5 guys.
His takedown defense was improved against Khabib, but the amount of fools he committed definitively helped
In a nutshell, he was immensely talented, but he would need to be very serious about his training and correct his skill gaps to be able to have a change with the top guys at 155.
You can't be a top fighter in a deep division as 155, when you are constantly parting, drinking, drugs, etc ...