So what I think I hear you saying
@Johnny B. Goode is that in 2017 or so, there was not anything you could buy directly, as you referenced - such as a "powerful building". I bought diamonds then for land squares, I think I was so noobish that I actually paid for a pesky blueprint too, and bought things in events, an extra this or that (way before fragmentation).
For me - I do count my 2nd or 3rd purchased CHERRY BLOSSOM set as "powerful building", but then again - all I had to do was have a few frogs jump efficiently and bought the chance to do that more times than were given to me for free (or earned).
So we did have that back then too - kinda, sorta - but I think you're saying it wasn't as rabid or pervasive or ubiquitous or as "in your daily face", as today.
I agree the player base had the sweet spot game here, and I often wondered "how are these guys doing this, this way, for so long"?
We know the answer - massive growth of the player population and from that, they kept their accounting beans in order by volume. Now it seems player counts are way down, and things cost most and there is a price tag on almost everything.