I'm going to explain this as nice as I can because I'm pretty sure you're mentally deficient.

This is what was said:

I saw a picture posted here of an early Ronnie and people were debating whether he was natty or not, and then OP posts a picture of the most athletic man ever to live looking large but not freakish and he's obviously on roids?

Following so far? If you see, I've bolded one part in particular. This means that I want to to pay close attention to it. No, not because it's going to run away, just look at the words carefully and try and assign meanings to them. Might be hard but I know you can do it.

The bolded part implies that because Bo Jackson isn't freakishly large that he might not have used steroids.

I replied with sarcasm stating:

Because PEDs are clearly only used by bodybuilders and only to get as big as possible. There couldn't be any possible benefits to steroids other than size!

My point was that steroids are not only used to look like a freakbeast, but for a multitude of other reasons that would help an athlete get to the top of their sport. Check out /r/steroids to learn about the various steroids available and their effects on the human body!

You then went full retard and said:

He's saying that Bo's genetics obviously beat the shit out of Ronnie's as he was probably the most athletic person ever

Implying that athleticism has a direct effect on muscle size, and that having genetics which allow you to excel at sports would be superior to muscle building than genetics which would benefit maximum muscle growth.

yet people think that Ronnie at his first Mr. O was more likely to be natty than Bo at a much more reasonable size.

There is this fun concept called "specializing". It's where you train for one thing in particular, to get good at that particular thing. Ronnie Coleman used steroids specifically for gaining as much muscle as possible, where Bo Jackson could have used steroids for recovery, strength, speed, or even muscle size.

You then stayed in full retard mode:

If you're actually telling me that better athleticism in football and baseball (both in which he went pro) does not correlate to muscle size then you're grasping at straws

That clearly isn't what I said, but is no less half-true. Athleticism does not determine muscle size but muscle size can benefit athleticism. Can you be athletic and gain muscle? Yes. Can you be an un-athletic fuck and gain muscle? Yes.

I hope you learned something new today and I look forward to your future contributions of finger-paintings.