I know we don't like justifying sets based on surprise factor, but if someone has an Aerodactyle / Azelf in their team, I'm 100% going to assume it's some lead set and choose my lead accordingly. Infernape, not so much-- of if we WANT players to have that expectation (expecting this set), than we should have it in the analysis.
This ability to anticipate obvious leads and shut them down at team preview is what basically killed the lead game/distinguishes DPPt from BW in terms of leads (downfall of over-dedicated lead sets). Infernape is still Infernape, with fast/powerful STAB attacks to benefit the team even after SR is put up. Plus, having cool options like Endeavor, Counter, Taunt, Encore, and Mach Punch is what sets Infernape apart.
Personally, I don't think lead ape is a game-breaking (or even great, just barely "good") set by any means-- but then, that can be pretty much said about ALL of Infernape's sets this metagame. IMO, this is one of its better options. I'm not going to defend it though if others disagree.
"Hmmm... a name for this plan..."