are you talking about actually splitpushing, or afk farming? splitpushing counts as an actual strategy IF they are actually splitpushing (if they are actually pushing and getting towers).
The latter is called "afk farming", where you either just shove waves in sidelanes with no plans for objective control or destroying towers or such, or just straight up freezing the lane at the 40 minute mark.
Both of these versions of AFK farming are technically griefing, as they make it seem like you are doing something useful, when really you might as well be just sitting in a bush toplane at 40 minutes. (unless you really need more gold, which it may just be better to teamfight depending on the circumstances)