The problem is that the system judges based on statistical numbers. For a somewaht relevant estimation based on numbers, you do need a certain samplesize(scientific relevant usually is 2000+)
However, most players have a far lower samplesize, so the estimation is prone to flaws, as there are alot factors out of the players controll in soloQ.
So Rueian is right, since people rarly will have 1000ranked games in a season, that would be ~3-4rankeds a day...
i for example reached plat 5 last season, with nearly 70% winrate and only ~70 rankeds played total.
I'd argue that plat 5 doesn't really reflect my skill level.
Your rank only really reflects your skill if you frequently play rankeds...