A couple of things to remember.
More games now = more chances to have a high scoring game.
Up until '83 only 6 teams from each conference made the playoffs, with the top teams in each division getting a bye in the first round. NBA playoffs didn't go to 16 teams until '84. The 1st round was only best of 3 in '83, then was best of 5 from '84 until '03. So a lot fewer games (and a lot less chances for big scoring outputs) in the past. To put some numbers to it, in '81 there were 10 total 1st round games, in '91 and '01 there were 32, and in '11 and '21 there were 43. If you want to add in play-in games, then that's 6 more games in '21.
But also remember when comparing different periods, overall scoring can change greatly. Here's the average playoff scoring over the last 40ish years.

It peaked in 1985 with 114.7ppg, from about '94-'13, the total average was 94.2 with lows of 87.6 in '99 and '88 in '04. But now it's been trending back up sitting at 111.7 currently.
So any playoff game from now compared to '94-'13 will have ~20 extra points per team that needs to be distributed, and we know that's not going to get distributed equally amongst the team, it's going mostly to the star(s).
Also looking in the past, there's probably a whole lot of big scoring outputs you never remember. In '85 for example, Bird led the way with 3 40+ point games, but Rolando Blackman and Alex English both had 2, and Terry Cummings and George Gervin each had 1. As an honorable mention, Mike Mitchell who most people probably never heard scored 37 one game. Add 11 more games to the first round, do we get even more?