Some interesting points, but again context must be taken into consideration. In those times there was a relative abundance of classic 10s able to drive team forward and be prolific themselves. Not so much today, as defences have evolved, becoming increasingly more athletic and intense. That made classic 10s, with their individualistic style based on creativity and skill, almost obsolete. You won't see anyone nowadays consistently taking the ball in their own half and bossing the game from goal to goal. It is literally impossible to do that anymore, defences are closing down and pressing too quickly. But even in that context, Messi is still able to play in classic playmaker style on the highest level, and outscore them all. He would arguably be even more unstoppable in a previous era, his skill level is that high, and he's more physically resilient than most classic 10s were.
There has, and never will be a superior or more defensively imperious league above 80's and early 90's serie A. The high press of today is good... for this era. In the time of 2pts for a win, it would be suicidal, and the quality of midfielder and their dribbling ability would have a field day beating the high press and strolling on to goal with only a discombobulated backline to take on.
In that era, a man marker, devoted solely to taking out the opposition's most dangerous player and ushering him into packed, unwavering defensive units was the thing. It was phased out over time because of how much it compromised the defensive team, and more importantly, with the arrival of 3pts for a win.
In short, to ever get a league with the defensive quality and superiority of Maradona's Serie A, you would need to go back to 2pts for a win, which would make defensive fortresses a thing once more. No player who has arrived, post-2pts-for-a-win, has any comprehension of what it is like to play in such utterly stifling conditions, but even then, Ronaldo played in a Serie A that is miles ahead of anything since in terms of defensive class.
The notion of Messi being 'more unstoppable' in the era of Maradona is, frankly, absurd. To even produce at 80% current level in those times would be incredible. Platini, Zico and Maradona were incredulous for putting up the numbers they did, Messi's goal-rate, even if it was just 5 goals more than them, would be phenomenal. You can absolutely forget about the numbers we witness these days being translated to that time, however.
The point was not whether Maradona would score more goals if he played further forward that's debatable. It's whether he'd hit these goal scoring heights that is.
The interesting thing about Maradona is he was a prolific player well before Messi was in terms of age. At 15(!) through to 21, he had 116 goals in 166 games. It's only because he was so utterly dominant playing further back that it became his thing. It's a catch 22: do you want to grab goals and not control the game, or completely control the game and hope to nick a goal in the process? That was the conundrum for managers handling Maradona, and it's over time that his finishing declined because he was no longer deployed in the position which would see his frequency of shots remain high and finely attuned.
The trajectory Maradona was actually on is superior to Messi's in terms of equivalency per age. He started banging them in earlier and showed no signs of decline if he'd been left to do the job he was initially put in teams to do. I will say, however, that the moment Maradona set foot in
that Serie A, his numbers would have dropped, as would anyone's, because of both the quality and cynicism of the league. Even for Barcelona he had his ankle destroyed and it would no doubt have been worse if he was putting up insane numbers in Serie A - the simple way to put a stop to that (prolific scoring) was to take out the player, which is something Zico and Van Basten succumbed to.