@Rebecca181, as @Kelly149 points out elsewhere in this thread, having a 4.8 overall rating would be exactly the same as having 80% 5-star ratings IF the only other possible rating was 4-stars.
However, as we know, there are also 1, 2, and 3 star ratings, and those drag down your overall rating numerically much more than a 4-star rating.
The big advantage of the 80% 5-star standard was that 1,2,3,and 4-star ratings were all treated the same: they just weren't 5-stars.
But now, to maintain a 4.8 average:
You need 4 perfect 5-star ratings to balance out a single 4-star rating.
You need 9 perfect 5-star ratings to balance out a single 3-star rating.
You need 14 perfect 5-star ratings to balance out a single 2-star rating.
You need 19 perfect 5-star ratings to balance out a single 1-star rating.
This gives outsized power to a guest threatening to give a 1-star rating.
That's why 4.8 isn't the same as 80% 5-star ratings.