Seeing as I coined the term with a very clear idea of what it should pertain to, I think I'm able to explain it quite accurately:
It pertains to fast moving defenders that also have an element of attack which allows them to handle stamina combinations. RF being the prime choice for optimum grip and aggressive movement. Generally they're quite heavy to make sure they come off best against other attackers. Like attack types they usually win by KO - except unlike attack types, they tend to do this against other attack types as well as stamina types, rather than trying to do it against defense types.
The latter part is the key difference from RF Defense - RF defenders lack the ability to handle stamina with decent reliability. The reason for this difference is basically because as a result of this things like Duo BD145RF and Diablo BD145RF have very different applications, Duo being solely defensive (and better at that) to the exclusion of notable attack ability and very poor stamina, whilst Diablo sacrifices some of that defense to be less overspecialized, making it a balance type.
The reason I went for Anti-Attack as the term is two fold: first and most obviously, they generally directly counter attack types, being well suited to (and often singlehandedly altering) attack based metas. Secondly, the term attack itself is included, as they have an element of attack, so that's kinda neat.
The main reason RF/R2F/LRF are the only tips seen for it is there hasn't been a defensive wheel that could KO on anything else. MF-H Basalt Kerbecs TH170WF could have been categorised as that initially, replacing grip with momentum for the head on collisions with the entirely left spin attackers (though it still did well against gravity even in right spin), however as soon as Scythe caught on it was no longer able to reliably handle every stamina combo (and previously LTSC were kinda a pain as you had to bank really, really hard to get them, though it was a reliable method if done correctly).
Basically, RF/R2F/LRF aren't necessary for a combination to be an Anti Attack combinations, but it's rare that there is a defensive setup that can handle stamina with any reliability on any other tip.
While the term is new, the tactic is quite old, MF Libra CH120RF would fit into the category quite well, for example.
Main reason I started using it was because people were calling things that failed against defense, which is very common in most metas, and did best against attack, which is the rarest of the three main types in most metas, "anti-meta", and (if memory serves me right) both Uwik and I, and a few others, were getting very, very tired of that silly name, Uwik pointed out the need for a term to be used in its place, and I came up with that.
To be fair, Anti-Meta pertained to RF Defense as well, however this was largely because at the time there there was this weird idea that defense types don't move - something which only holds true in any given generation through circular logic or Tuned Bearings (i.e. illegal modification) - Defensive Zombies can move extremely aggressively as long as they're not using tuned bearings, Weight Based Defense traditionally used SG Metal Ball which moves aggressively enough to make force smash very useful with the type (and have an even better option in Customize Metal Change Base, which moves aggressively) - though to be fair Weight Based Defense could be considered Balance. Circle Survivor Defenders can also move aggressively if the SG is wound, enough to allow them to KO Spiral Change base zombies.
In HMS, defense is pretty much neglected but the main RC for it, Bearing Core 2, does move a fair bit, especially as it gets more worn.
MFB were heavy enough to use RS (a tip shape which had failed miserably in previous gens), but CS often performs better when moving. Of course it seems this idea gained or at least had a large amount of popularity when WB was the only defense tip, and sure, it probably did do slightly better when it wasn't moving - as it faced a lot of left spin attack, and to not move required a weaker launch which helps somewhat, and because going near the tornado ridge was probably a bad idea for a tip with only mediocre ability to catch it, and even more so because of how inadequate a defensive tip it was when faced with RF attackers (especially after Libra was banned)
Of course, now this idea is finally receding, things like Duo BD145RF are generally able to be called defense without anyone getting nitpicky, and while the term RF defense is there, it is more of a description than an actual name.
Uhhh, sorry if I got rambly at the end there, but the first part should answer the question anyway.