I think mIRC could get the MAC address from the computer and send the server, so IRCD coders could implement the ircd to ban/akill/gline from a MAC address mask.
That would prevent users with dynamic IP from changing their IPs and re-joining the network or channel.
Would that be funccionally?
This would not work since MAC is not part of sIP nor dIP address, and don't stop anyone to get a packet to travel though internet. The user can change his MAC even easier than changing his IP. If IRC started to claim a MAC for ppl to connect it would take less than hours before all the popular IRC cients are avalable in a pached version where the user can change their MACs at will. In fact, it's a good reason to believe that this version would be more popular than the original, because ppl tend to want a version with as few limitations as possible.
Assuming you want to keep the trolls out of your channel, you allready got all the tools you need. Ex. you can run an account system where your channel is in invite only mode, where ppl must send their account name and pw to get an invite. The only reason why not few or even a single owner does run his channel this way is because their guests who are not trolls don't want to be part of a tyrannic system where few of the members got the power to put a final stop for a member to join. Ppl in general like trolls in their everyday grey boring life. If this wasn't true, you would have no problem with trolls because they wouldn't appeal to your guests, but be ignored. We know that this is not the case in the real world. The conclusion is unescapeable: What you basically seek is a system where the members are protected from themself, who do not want to be protected. Ppl love trolls, and the second trolls are banned in a channel, they seek another.
This was the technical and humanal reasons why adding MAC as an constant to do access control won't work.
The world rest upon reason, and the second you try to exchange reason with access control, you will get, with an absolute necessity, tyranny. You should be happy that US NAVY were forthseeing enough, specifically to order what is known to be an OPEN PROTOCOL, and not half open or closed. If internet was invented in Sovjet, this may very well not be the case. Internet is ran by what we call IP, here under TCP/IP and UDP-TCP/IP, and as long as this is the case, we will have liberty on internet. This means internet does not favour tyranny. This doesn't mean tyranny is impossible on the net, but it means that they who want liberty, can get it, by seeking at the right places.
There are some types of trolls who are only anoying. They are not interesting in any way what so ever, and don't function as a glint of light in a grey boring life. To stop these trolls to embitter the etablishment, you may put up a bot if only function as an ignore filter producer that sends notices to the channel what IDENT/IP masks if type of troll is behind it, is totally not interesting, not even to they who are found of trolls. This bot can controlled by the guests, and all the guests can choose their own level of cencorchip, much like poll system where they got a script that filter all msg's that got more than so and so may votes.
I think the simple answer is found in the Internet Protocol itself. MAC addresses are only sent within a local area network for routing purposes. The MAC address of an individual computer is stripped at the gateway (however you want to define that), and the MAC address of the gateway is usually used for routing purposes. Thus, the MAC address seen at the IRC server, if one is seen at all will not be the right one. Actually, it is likely to be the MAC address of the IRC network gateway - so choosing that MAC address is likely to kill all traffic.
There - a much simpler explanation without bringing the "might of the US Defence, defender of the entire world" into it!
p.s. Perhaps you want to re-read your history on the origin of the internet? As well as reading up the roles of IP, TCP and UDP. Your ignorance is showing.