And of course there are many, many people who refuse to play D&D. Or will only do so as a last resort. Tastes of point based over level based systems, etc etc.
I'm glad that's your experience but it is not mine. When I started playing in '78, there were already plenty of people who were familiar with D&D but wouldn't touch it with a barge pole. By the mid-eighties, I was the same.
This.
No, really, D&D had a pretty bad reputation in our area in the eighties. D&D was THE 'hack & slash' system; nobody who valued the opinion of others would admit to playing or actually enjoying the system. When 2E came out it was the first tiny step towards an acceptable rpg (well at least there were NWPs now...) but it definitely took 3E for D&D to arrive in the modern age and be able to compete with other systems.
Don't get me wrong, I did enjoy playing AD&D 1E at the time and even started a campaign but D&D really was regarded as an inferior and outdated system by many.