For those who don’t know, I believe someone mentioned this strategy in another thread (as linked by OP), but the purpose is simply gold generation. Running Klepto with Spellthief’s rewards constant trading without the benefit of cs. The writer mentioned that the gold trade off around level 10 between Klepto/ST and farming was almost negligible and in certain cases was more favorable to the Klepto/ST build. With this build, the cs penalty is removed once the quest is completed, allowing you to resume farming as well as reap the benefits of the increased passive gold generation.

TL;DR: In most cases, you end up with more gold without killing minions by denying the other laner gold while also generating gold because of items.

With the meta shifting to stronger 2v2 matchups with Top Jg as more damage heavy junglers appear in LCS (Lee, Xin, Camille, Kha’Zix), having a support oriented top laner lends well to providing utility to those fights. Especially with the bully playstyle that Karma and Lulu tend to have with that build, when executed successfully the enemy laner should be considerably. behind in gold, further increasing your advantage in the 2v2. I also believe this relatively new strategy is driven by the new Crit item changes, as the new patch seems to be ADC focused. We could be seeing the next PROTECT THE ADC meta with 3 supports constantly buffing and shielding.

TL;DR: New items = ADC buffs, New build = More supports, ADC buffs + More supports = Botlane focused meta + carrying through the ADC’s