It's not to achieve high concentrations, it's to disguise the fact that it's been cut at all.

Distillate that's minimally cut will typically be very very thick. The more it's cut, the thinner and runnier it will be. Customers figured this out and started equating runny pens with low quality.

Dealers basically responded by using cuts that aren't obvious. This doesn't make the concentration any higher but fools the end user.