Question about Middlemen

So i sent friend request to about 4 middlemen to ask them a few question and so they can me my MM for the trade. And to my surprise 2 of the middlemen declined my friend request. The fist one that did so was Sarcasm, and what i found weird about it is that when i sent him friend request and posted on his profile (it says to do so on his profile) after like 1-2 hours i got added by 2 Sarcasm imposter which i trolled by telling them i do not need MM (they asked me if i needed MM and i doubled checked to be sure that they were imposter, the fact that the real Sarcasm was still pending in my friend list) and after few hours the Sarcasm declined my friend request. Which possibly can be his alts but that is just my speculation. The second MM that declined my friend request was Wuvs, woke up today and bam he is gone from my friend list (Pending friend request that i sent him not that he accepted me or something).

I do not want to be rude or anything but being a MM and just randomly declining friend request means that you do not want to be MM so why even offer such service.

As MM are very careful with their accounts, for MMing for bad parties can have effect on their account, they won't trade everybody. As above said, they have also some rules of how to contact them. But they also are completely free to reject any MM that they don't like, whatever that reason is.
The ignoring of invites is often part of their policy to ignore anybody that did add them while they where away etc. For they get so bombarded with invites that they cannot help everybody. This results often in the MM's saying that only ppl who are done negotiating their trade can add them. Too often it is that people add them and they didn't even finalize their agreement, wasting the time of the MM, and some refuse to help those either. In my talks with a couple MM's not too long ago they told that they don't MM much, they have so many to reject for either party is shady, that sometimes its months before they get to a trade that can be MM'd in their opinion.

I have read their rules on their profiles so yes i followed all of them and the reason i posted here because they are marked as MM here on steamrep.

"only ppl who are done negotiating their trade " I have and because it takes like more than a day to get accepted into their friendlist when they DO accept the other user that is supposed to trade with me is not online. I mean i understand that MM can not accept my friend req in a instant but at the same time it is not my fault that they rejected me only because the other user wasn't online.
The only one good MM that i heard about is Vintage Cobra but he is away quite a lot, so it is hard to actually have him online and the other user i am supposed to trade with.

VC wants MM's to be done within 3 minutes or some. He's from eastern europe, and is mostly on at USA evening times for trading.

Keep in mind that a MM may be busy and thus declining further MM requests until the current "queue" is dealt with. First come, first serve and if I can not serve them timely, I am not going to pretend I can.

That is why they should have this system where they accept only 10 people and lets say he was MM for 5 trades and has 5 more people that can not do trade atm so he can add another 5 so the limit is 10 people, that way if you got your friend request accepted by MM you know that you can do the trade within a day.

They handle it one by one. There is no saying how long a MM can take sometimes.

That would turn MM into a full time job. Keep in mind that we volunteer our personal time to make trading safer for the community but a lot of us are, just like you, gamers, traders, people who enjoy watching TV, spending time with friends and so on and so forth. We do this out of good will, not to keep our daily schedule filled with middlemanning online trades.

In addition to that some MM like VC get so many requests that he would need his own secretary to uphold the system you suggested.

Oh, he has a "secretary", but thats another story

NO he got a secretary for a very special reason. Yep.