okay think of it this way...
to enter the UK you need a reason i.e., tourist, fiance, work permit holder, spouse, dependent, etc
not all of these necessarily need an "entry clearance"
for example, when I entered the UK in the past, I was a tourist. My visa stamp said I could stay up to 6 months, can't work or seek public funds.
now someone is requesting to stay (or were denied entry in the past or require a clearance etc etc) in the UK so they need some sort of proof that they will take care of themselves or have someone to help them out. I look at the entry clearance as another hoop to jump before you get to the country so if you need to sort anything out before you get there it is done... instead of in a crowed immigration line.
I see what you mean though by the sematics of what is actually on the sticker or stamp. I am going over on a work permit and from what I heard last it is just a stamp... no fancy little pictured sticker like some of the other visas.