the amount of Summoners overlooks the level of them
Exactly. This does not count BCX's, it counts upgraded cards as 1, because you can play 1 card.
we could have a half million of level one summoners and those wouldn't be all competitive players
That is very unlikely. Because many earlier editions summoners have been combined to higher levels.
Let's take Alric from Beta, for example. Total cards printed are 76,269. Yet cards in circulation + burned (both regular and GF) account for 9,039. The huge difference comes from people combining them, and thus reducing the circulating supply.
so I wouldn't say that there is an over supply of them
No, of course there isn't. In fact, if we account that many of us have multiple summoners we use (without counting the ones we rent out, because those are used by others), we can draw the conclusion there are fewer unique players in the game than the DAU may give us the impression.
It is my impression as well, we will hear again that fatidical "why the cards are so expensive?".
I'm sure we will. It's cyclical. But once someone understands Splinterlands, it makes sense.