I thought all functional ones were exempt?
Depends on where. Country or region of origin is everything. Whilst I think it's a bunch of BS, some places will require you legally to have said disclaimer even if the cookies aren't your own. Hence just including Google Analytics and Adsense are enough to have the EU tell you to include such a warning.
Thankfully I'm in and hosting out of the US where we basically say screw that, but in Europe? I see people proactively adding these warnings even if they don't need them, JUST as a precaution as the hammer comes down harder and faster on site owners over things like this.
Aka a good engineer is always a wee bit conservative, at least on paper. It's called over-provisioning, you figure out how much you REALLY need, and then you apply more as a safety margin. You need a bolt that can handle 30,000 pounds of proof load, you might think "ok, a #2 7/8ths is sufficient"... and that's why you put in a quarter inch #5 rated to 85k.