@mavica_again
Because 5.01 was the last stable release, and came out in 2013.
The new 6.00 stable build just came out in October, so only relatively new live discs would have it.
Suppose they could have switched over to the 5.31 beta, but that still didn't come out until 2020. So even if they were willing to build a non-stable release into their disc, there was still a huge amount of time where they were stuck with 5.01.