I think you are misunderstanding what the devs admitted.
They didn’t release an idea they thought would work, to realize it was flawed only after release.
What they did is release an idea they realized already before release that it was flawed, but didn’t have the time for the planned release date to revise.
By their own admission, they released a broken system they knew they had to fix in later patches: this is basically by definition “releasing an unfinished product”.