When we bottle our brews to let them carb and condition, they contain yeast.
This yeast is NEVER removed.
You wouldn't want to get rid of of all the LIVE yeast; or your bottles would not carbonate.
If there is a single yeast cell in suspension, the priming sugar would make that cell multiply until there was enough yeast to ferment out the sugar, they would then settle to the bottom of the bottle. So, just because yeast is evident in the bottle does not mean large amounts of yeast weren't left in the primary and secondary.
There is more than live and dead yeast in the bottom of a primary and secondary.
While people report long primary times with no flavor problems, these are not double blind studies. These people did not split batches and secondary one (or bottle sooner) and leave one on trub. We can't know if it would have tasted better or not.
Most award winning brews are secondaried. However, some are not. Many people who proudly proclaim their lack of secondary are kegging. Racking from a primary to a keg, is secondary bulk conditioning.