Dilution is a problem for reasons other than mere viscosity loss, but some oils can almost shrug off these other effects and make it purely about viscosity.
The HPL I ran in my accord got to 4% dilution in only 4400 miles but the engine is immaculate, wear is vanishingly low, and the oxidation and nitration levels suggested that the oil was basically ignoring the dilution. I'm currently experimenting to see if I can go 10k OCIs on a known diluter with HPL. So far, all indications are that it will make 10k without issue.
Not all dilution is equally a problem-- some oils tolerate it it remarkably well.
The main things you have to worry about (besides viscosity loss) are oxidation and TBN depletion. This is why some non-HPL oils might not make it on longer OCIs in high dilution cycles; those oils lack the TBN and oxidation resistance to go the distance with deposits held in check.
That said, I'd consider some oils like Euro FS 5w-50 to be a good choice for heavy diluters, it's just so hard to find that I'd rather run HPL PCEO for about the same cost. Euro FS 0w-40 is also a great choice but probably not thick enough or shear stable enough to keep KV100 in the face of both heavy dilution AND high miles.