Bunnyhopping is the primary way of navigating a map and its initial removal in 2001 was due to Counter-Strike community complaints. It arguably made sense for a game that is devoid of movement, therefore making sure that the gameplay is kept intact to abide the majority. Half-Life and Team Fortress Classic on the other hand are games where this is key and their skill to a large extent stems from being able to move around.
The removal at the time was rather controversial, some people seeing it as an obvious fix whereas others saw it as an engine feature. Combining the two features jumping and strafing resulted in quite a game changing mechanic where many saw it as great for improving gameplay and setting both the learning and skill curve higher. Bunnyhopping can easily be compared with that of other engine techniques such as rocket jumping and wall strafing, neither of which were altered.
Today in Half-Life, server plugins have to be used to remove the prevention which causes client lag whilst other people have moved to modifications such as Adrenaline Gamer. It has caused a large split within the growing Half-Life speedrunning community where some have opted to run on older versions from 2001 (220.127.116.11) with a newer Steam engine release and others with old varied modified Steam releases. It has, in a nutshell, created a muddy mess of unclarity that has been growing into a bigger problem every year with lack of proper rules, the sole reason being due to the jump cap.
We can draw a clear distinction between id Software which recognized the response from the community upon the removal, ending up revoking their cap. Whether you support bunnyhopping or not it will continue to be an essential quirk to many and so it makes sense to integrate a multiplayer command. Thereby servers that want a competitive format in TFC, HLDM or bhop maps can choose to disable the prevention server side without worrying about lag.
Since the mechanic really isn’t defined as a glitch but merely serves as a fundamental piece in how the engine works; and so, the Half-Life single-player should not be affected by a change invoked by the Counter-Strike community. Without the cap this would have no effect at all on the casual standard Half-Life experience, which I personally strongly support as well.
The proposed suggestion is “mp_bhopcap 1/0” which affects solely the multiplayer, which is, and was, the bunnyhop cap’s initial intention. As for single-player, the cap simply doesn’t need to be in place, much like how accelerated back hopping is still in the Half-Life 2 single-player, but is not in the separate Half-Life 2 Deathmatch game/mod. The variable is defaulting to 1 so that the existing server setups have no change on update, and can be turned to 0 by the server admins who do not want the cap.
YaLTeR has already implemented the fix on github: