well, to be fair, micro-optimisation is always context dependant, if there is really a check of every instances with pick by uid, that would be bothering if your game needs it, but nothing if it was not that used in your game, same goes with collisions optimisations (even though those can be easily the bottleneck), etc... But in that case, if the pick by uid would be wasteful, that would be dissapointing.
always have a critic eye over ashley's blogposts, as he tries both to talk to people that can go really far in wasteful design and also he tries to be general and so, something true can become false depending on how you did your game (the recent render cells are a micro optimisation for a lot of games, it can even be worse, but in some defined cases, it is nice and can save out a lot of time), learning to identify what is really causing trouble is something that will help you in the long run.
also have a critic eye over other people talking about their experiences too, for the same reasons.