It is not as simple as that is it?
Take Kilian who is sponsored (ie full time professional), he spends his life either training or racing. And whether or not he did, he certainly could have spent weeks receiing without any of the constraints of normal people.
Is that really compatible with the Ethos you claim? He is a member and record holder.
The ethos requires those who have their bags carried to carry bags for others. But that is not simple either for those who live far away or abroad. I will wager Killian never does his share, or perhaps not even any.
Some have a group of massively experienced supporters who do it every week and are local. Others have the only ones they know, who are pretty much as oblivious as they are.
Big advantage to former group. Route knowledge in clag does matter. And if they only way you can get it is buy it, why not: if it helps to level the playing field.
Ive seen rounds destroyed beyond redemption even before great calva because of inadequate supporters.
It seems to me it is another of these oversimplistic "feel good" rules in what is inevitably a murky world. There is no such thing as a level playing field. So why pretend there is? If supporter use a taxi they are using professional paid support. There are only shades of grey. If you have a paid physio patch you up either before or during. Ditto.
Surely all that really matters is whether they got round witnessed under their own steam. That is the challenge. Some have one supporter. Some have a dozen.
Amateur athletics got itself into a major mess when it started arguing the boundaries of what was professional or professional support. It was a mess that blighted Liz Mcolgans career, and destroyed the career of her coach.