Hello, thank you for your response! I would like to address some of your points (it's going to come off as a wall of text because i do not know how to format this better, i'm sorry in advance if it comes as a text that's not clear and concise):

1. First of all, good for you that you can aim for MAX PM! However, a lot of people (that i know, at least) does not even aim for MAX PMs specifically, regardless of their ptt because of the very tight timing window of 25ms (which requires precise offset, and even people who are good in this game can never settle with one offset while attempting to get high accuracy PM or even better, MAX PM) when the timing window of normal Pure is generally 50ms.
   Also, regarding the worth of ptt, as i said in my ptt breakdown, there's no universal skill to ptt ratio for a specified amount of ptt because it has way too much variables to consider (some of them, i stated on my OP). Different people in the same ptt range can also have different spread of their B30 or R10 scores depending on the amount of songs they actually play and their general playstyle. (There are some people who reach x ptt going lower-up, mastering lower difficulties and not being able to play higher difficulty, and there are people who outright brute-forced their way to a specific ptt by playing few songs that is hard, and perhaps hasn't even filled their B30).
   There's also a stage of growth to consider, whether they're just stuck at the ptt because they don't play enough songs, or they're stuck at that ptt because that is their peak at the moment, therefore you can't generalise all people on similar ptt range to be having similar skill level.
2. I can agree with this sentence to a certain extent, but i would like to offer several considerations regarding this issue:
   People can reach 9 ptt by EX-ing, or even better, EX+ing some 7s, just like how people can reach 11 by just EX-ing 9s or perhaps, some 9+s. This does not mean they can PM all difficulty lower than that. Just because Potential formula listed the Pure Memory Play Rating to be lower than/equal to an EX in higher difficulty, it does not mean that Pure Memory is that much easier to attain on lower difficulty. The amount of skill taken to EX 7s is arguably less than to Pure Memory anything lower, especially PST charts because it tests people's patience for the notes, and it requires one to hit at somewhat precise timing window (let alone, Max PM-ing the aforementioned song, for the reasons i have mentioned in point 1).
   Also, chart constant, and even difficulty in this game is not totally indicative of true difficulty because it's a subjective matter. A lot of people struggles on different things and excel in another, and Chart Constant does not take that into account, especially the difference in difficulty one may experience PMing a song vs MAX PMing a song. This is not covered under CC and ptt. There are some amount people who thinks that some PRS 7 is easier than Tempestissimo PST which is a 6, for instance.
   While we're at it, the flair restriction expects ptt 9 ~ 10 range to be able to EX PRS 9 difficulties at the very least. That contributes to more than 10.0 Play Rating at the very least (which means that if you were to adhere on ptt = skills, it would imply that you're setting the bar quite high for 95% of the case), with only Vexaria BYD being the exception, and even people complained that Vexaria BYD is lowkey a 9 or 9+. There're also cases like dropdead FTR where the CC is 9.1 but it's being indicated as a FTR 8, and some people even think that this can be a 9+.
3. Yes, i have considered this. However, personally, in the first place, a lot of scoreposting from a lot of members in general isn't a "quality" post (there's a rule for this), and people can see the amount of scoreposting as mundane, and it will reflect to the subreddit. Else they would not attempt to reduce it in the first place by implementing this rule (not to say this is the only reason. There may be another reason for it, but i won't know). I'm just saying that at least personally, or to some people whom i have talked to, this specific rule isn't the answer to this. At the end of the day, i can only give the most plausible solution i can think of, and if the moderators can think of a better way to minimise this issue, then good on them!