I can't count any more PMs coming in for me.
I have just the opposite experience, no one has ever asked me for any service related to merit - neither to give them away, nor to sell them. Maybe the thing is that those who do it target merit sources or have some other criteria that my profile doesn't meet

It's very hard for an average poster to rise through the ranks, hell, even a decent poster probably won't achieve the sufficient merit to become a Hero within the timeframe it takes to get the required activity so skipping the queue by donating seems like a win-win to me.
Maybe then it's time to modify the current requirements, which are obviously too difficult for most new and some old members. If 1000 merits is the current request for Legendary rank, maybe we should lower it to 750, and Hero from 500 to maybe 350 or 400 merits. Of course, the question arises what to do with lower ranks, because in my opinion Jr. Member is very easy to reach, just like Member (1 - 10 merits) but even 10 times more is needed for Full Member rank which is too much in my opinion.
Maybe the ranks could be tweaked a bit. Legendary should probably follow the other ranks at 750 merit and in doubling with every one. I'd like to see an additional rank for those very high merited users. Some other perks would be nice.
It's very hard for an average poster to rise through the ranks, hell, even a decent poster probably won't achieve the sufficient merit to become a Hero within the timeframe it takes to get the required activity (...)
What most people don't understand is that life's too short to care too much about Merit. I've often wondered how much money and energy people lose when they spend their time desperately posting spam and begging for Merit and coins, instead of putting that time and energy in a real-life job with a real-life income (fiat of course, but at least it's better than nothing except for a lot of frustrations and in the end seeing your modest profile getting banned for spamming or begging).
People should come to these boards to learn, participate (that's not a synonym of shitpost) and have a good time (probably in that order).
That's like saying life's too short to care about money or a promotion at work. It's those things that often give people a better life so that's why they desire them as ranks here = promotion and more merit = more money and time saved if they can get it. The majority of people who spend their time here desperately trying to achieve ranks or earn from from campaigns are probably doing it because it's one of their better options. Would you rather be unemployed or do back-breakign menial work when you can get paid from the comfort of your own home for doing some posting? Some signature campaigns pay a good amount of money and if you're from the developing world getting on a campaign like Chipmixer might be life-changing money so that's why people are desperate for merit/ranks as it means more money for them. If most of these people had better options they'd probably be doing them but sadly they likely don't.