As to your other points, Robinson didn't even make the Finals until Duncan. Sure, if he had lost to the Bulls a handful of times that is different, but the Spurs didn't even make it out of the West, which by and large was pretty darn weak in the 90's.
I disagree that the West was pretty weak then. I feel like at the time, the East was more like LeBron's East. You had that 1 dominate team/player with Jordan/LeBron and maybe 1 quasi-competitor in any given season like the Knicks/Pacers, while the West felt more like today's East where you have several teams that could come out on top.
From '91-'96, the West had 5 different teams with 60+ wins (UTA, PHO, SAS, POR, SEA x2) while the East had only 3 (CHI 3x, NYK, ORL). The West also had more teams in the 55-59 win range (15 vs 8 ).
Then look at All-NBA, West had 51 vs 39 total selections. 19 vs 11 first team selections. The West was tough, they had the better top end teams talent outside of Bulls/Jordan. (And part of this is what makes Hakeem's '95 run all the more impressive as they ran through such a strong West, beating the top 4 teams in the league along the way. Basically what Boston's going to have to do this year.)
There really is no question. Hakeem was a superior player to Robinson. It wasn't really all that close and anyone that really followed the NBA in the 90's knew this.
Also surprised so many think it wasn't close. Hey, I'm with the majority here, Hakeem was the better player. But from '91-'96 when both seemed to be at the top of their games, it was close (unfortunately it doesn't look like bball-ref has a tool to let you compare stretches in the middle of careers, only single seasons or from beginning of career to random point). From '91-'96, Robinson was 1st team All-NBA 4x's to Haleem's 2x. Robinson was 1st team All-Defense 4x to Hakeem's 2x, though Hakeem won 2 DPOY to Robinson's 1. Each won 1 MVP. Robinson finished higher than Hakeem in MVP voting 4 of those 6 years.
Maybe it's not fair to judge Robinson from ages 25-30 and compare against Hakeem ages 28-33. But during that period it was very close.
Hakeem had the longer career, was better for longer, and did some amazing things in the playoffs (where all time greats are made). No question about it. But from '91-'96, it was close.