Yes, it is. You rarely see knockdown texture along with the likes as spray sand and slap brush knockdown. These methods can still be used but you’ll see them with popcorn ceiling texture instead of walls.
A skim coating can still look great on your drywall but if you want to add texture, you should probably put the putty knife down and look beyond knockdown. The likes of popcorn ceilings can still be popular if you did like these traditional methods.