Also if you play limits where there are a lot of regs you get to know their games so you don't even need the HUD. But yeah I'm currently 18-tabling and I definitely play the player as well. Granted I have to make a lot more assumptions I wouldn't have to make if I were 1-4 tabling, but general hand-reading skills are similar. I assume a 14/12 is able to fold top pair to 3 barrels and a 40/2 isn't folding top pair ever. Just little assumptions like that where if I were paying more attention I could get a better read than using preflop stats for postflop characteristics.
Are there not stats that tell you these things as well? I remember people posting about stats such as % fold to double barrel, etc.
Turn & river stats require a hell of a lot of hands to become reliable. Also, it takes time to fetch stats that are not directly in your HUD but that you access through a popup.
Having a few models of typical player behaviors based on a few fast converging stats and only relying on advanced stats for very tricky decisions or post-play analysis/note taking is a sensible approach.