Because it’s true. As for your strawman about gulags, well that’s just dumb.
No I speak about the Founders as people who had great ideas, but were flawed human beings and made some mistakes. Probably their single biggest mistake is that the allowed slavery to continue. They had an opportunity to get rid of it. They were making a new country that would only inherit the laws they chose to. And they chose poorly.
There was never such an opportunity to end slavery for the Founders. South Carolina and Georgia, and probably North Carolina too would've re-joined the British Empire given the Empire's pro-slavery stance pre-1800. The king said as much about their slavery favoritism.
There would not be a U.S. without said tolerance.
Britain wanted its 13 slave colonies back and an immediate knock-down of 13 down to 10 would've either ensured the U.S. lost the Revolutionary War outright, or a second Revolutionary War within just a few years of Yorktown.