You're getting points and miles confused on several counts.

First of all, you don't earn any points at all at United's Mileage Plus Dining. You earn miles!

Second, there's a reason, besides semantics, that that's important. The value of one mile (at any airline that uses miles as their currency, certainly including UA) is several times more than the value of one hotel point at "10 points per dollar spent on hotel stays" kinds of hotel programs (which includes Priority Club, Hilton HHonors, Choice, Best Western, WynhamRewards, etc, etc, but does not include Starwood). One way to compare them (though certainly not the only or even necessarily best way) is that if you need to convert hotel points to airline miles, Priority Club hotel points transfer 5:1 to airline miles.

So by any measure I can think of, 8 Priority Club points is worth far less than 5 miles.

And thus I don't understand the word "only" in front of 5 UA [miles]. At UA, you earn 5+5=10 miles for the typical dine, and that's worth way more to me than 8+8=16 miles. I wasn't promoting Priority Club Dining as a great value to someone equally interested in miles and points, I was just explaining it for those, such as the OP, who already have more miles than they need, and now want to focus just on hotel points.