Okay, after a long conversation with adelikat, I was given approval to change some obsoletion chains if it will fit into the system of tiers.
Now the question becomes not, whether a movie must
be ubobsoleted, but rather, would it be accepted if it is submitted today
Explanation. To reduce the amount of arbitrary branches in the past, judges decided to obsolete runs by one another that were quite different. For example, SML2 any% was obsoleted by glitched. Now, if we imagine that the any% SML2 is submitted today, will it be rejected for suboptimality comparing to the current glitched? Because, when #4041: McBobX's Genesis Knuckles in Sonic The Hedgehog in 14:09.43
was submitted, it was rejected for not using the known tricks, which would lead to overall suboptimality. Similarly, if  SNES Chrono Trigger by hero of the day in 4:21:11.83
will be submitted today, I think it will be rejected for failing to be up-to-date with the current level of TASing.
Another reason to reject a movie is if its content is already present on the site in a better way. So if  NES Cross Fire "pacifist, no damage" by xxNKxx in 05:56.36
will be submitted today, we will reject it for being too similar to  NES Cross Fire by MESHUGGAH in 05:52.50
and being slower.
The last reason is having unvaultable goal but failing to achieve Moons by being boring. Not sure if such movies were obsoleted in the past, since they were most likely rejected in the first place.
So if you really want some movie to be unobsoleted, let's examine if it is eligible for Moons as if it is submitted today, and if it is not sloppy (represents the current standards/face of the site).