I honestly think the league is deeper now than it's ever been.
The league was not deeper then. Lesser teams means better players top to bottom. There would not be scrubs on the old league.
I can't parse this - are you saying the league isn't deeper now, and fewer teams means better players top to bottom? That isn't necessarily true, if fewer people are playing the game. A simple example - there are about 2x as many Americans now as in the 50s. If all else is equal, you'd expect about 2x as many good players today from America just based on sheer numbers. Bigger talent pool = more high-level players.
And there have been scrubs in every era of the league; we just don't remember them because, well, they're scrubs. And the Celtics of old didn't have many.
Can't underestimate that basketball is now a truly global sport, with the NBA as its unquestioned pinnacle. And everyone from stars to role players are staying effective through their mid-to-late 30s a lot more often than they used to. It was significantly shallower 15-20 years ago at Jordan's peak, though.
Global = more fanbase not better players. The league was weak in the Jordan years. But in Russell's era, which I might add was a full twenty between Jordan and Russell almost, teams were loaded with all americans.
How old are you, Fairweather?
Teams were loaded in the 80s too. This three all star thing happened all the time then. C's , 76ers and Lakers were loaded and you could have made two of today's teams with their talent levels. I beat their benches could tear up half the league.
No, a global sport also means a broader talent pool for players. The major influx of foreign players over the last 20 years speaks for that. Ginobili, Kirilenko, Yao, Bogut, Ibaka - 5 very good recent players from 5 different continents. And those are just off the top of my head - there are dozens of other examples.
When a few teams are stacked like you're mentioning, it's offset by how unstacked the bad teams in the league are. Like Moranis said, look at the rosters and records for the worst teams in the 80s. The league being top-heavy doesn't mean the entire league was deeper.
Bottom line, the NBA has the biggest talent pool it's ever had, and more longevity across the board too. That's led to a major increase in depth over the past couple of decades.