A person who receives real estate as gift while donor is still alive - must live in the gifted house for 2 years ?

I am confused here...

It says donee receives cost basis of donor.

It also says donee receives donor's holding period in the property for determining whether a gain is long-term or short-term.

 

So why does donee need to live in that gifted property as his/her primary house for at least two of the last five years before selling it  to be eligible for a capital gains exclusion of up to $250,000

 

If donee is receiving donor's holding period and donor is eligible for 250000$ exemption (by living in that property for last 2 years)- why can't donee automatically get that exemption? @rjs @fanfare @xmasbaby0 @Opus 17