In 61-62 the league average was 118.8 ppg (the Warriors were over 125). It was just a different era. Teams just went up and down the floor. The most impressive thing Wilt did that season wasn't score 50.4 ppg, it was play 48.5 mpg (he missed less than 50 minutes all season). There were also only 9 teams, 6 of which made the playoffs with the top seed getting a bye. To win the championship that season Boston only had to win 2 series, which was that way for much of Bill's run in the 50's and 60's. Having to win only 8 games to win a championship, quite simply made it easier to do. It also didn't hurt that the Celtics basically had at least 5 HOFers every single season.
EDIT: As a comparison, the year Jordan scored 37.1 the Bulls scored 104.8 ppg (that was 86-87), so Jordan accounted for 35.4% of the Bulls points directly. Jordan also had 4.6 apg so at least another 9.2 ppg (takes it up to at least 39% of the Bulls points). So doing the same thing for Wilt and the Warriors in 61-62, Wilts 50.4 ppg plus his 2.4 apg (4.8 points) were obviously a greater percentage at 44%, but not nearly as much as you might think before doing that math. For some further seasons, the 05-06 Lakers scored just 99.4 ppg of which Kobe scored 35.4 ppg and had 4.5 apg, which if you do the math means Kobe accounted for at least 44.66% of the Lakers points that season, or a greater percentage than Wilt accounted for. The 18-19 Rockets scored 113.9 ppg, Harden was at 36.1 ppg and 7.5 apg or 44.86% of the points (and that is clearly less as at least some of Harden's assists were on 3 pointers). And of course, we can't leave Lebron out. The 07-08 Cavs scored 96.4 ppg, James was at 30.0 ppg and 7.2 apg, which is at least a whooping 46% of team points scored or assisted by James. And for the cream of the crop look no further than the 16-17 Thunder at 106.6 ppg, of which Westbrook scored 31.6 ppg and dished out a whopping 10.4 apg or 49.16% (which is really probably over 50% when correctly accounting for the 3 pointers on those assists). I'm sure you can find other similar seasons, especially from the eras where teams weren't scoring that much.
Wilt had an incredibly dominant season in 61-62, but other individual seasons were absolutely in the ballpark when accounting for pace and assists. In fact, you can realistically argue that that season of Wilt wasn't even one of the top 5 most dominant seasons in the sport's history.