How is this alright?

Oh you sweet summer child, you know nothing of the Kayle of old when her ult would last 5 seconds.

Something of note is that while she can't take damage, she can still be CC'd so you can still knock her around, stun her, etc etc. You just can't kill her for 2.5 seconds.

Yes, broken things happen when a team has a 10k gold advantage and the team with the disadvantage stacks on top of the enemy Ornn and Katarina ults.