Cantiara @Piokilek is viewing it from an author's viewpoint. The idea is that the translators are already paid a flat fee for their work, so they shouldn't deserve more, but the way the web novel translation industry has developed is a little different, mainly being how web novels are very long and that they are serialized.
Translators are paid to do chapters, but they aren't incentivized to do more than they need, so if they are expected to do 10/week, they do 10/week. Of course, doing more allows them to get paid more, but some of them think of this more as a part-time job instead of a full-time job. Or, they just do enough to make ends meet, and enjoy the rest of their free time. Various reasons. But this 'slow' speed affects reader enjoyment, so there's definitely a need for some mechanism to incentivize them.
Then, Webnovel allows translators to choose to switch to a royalty scheme. In theory, if a book is doing well, a royalty scheme will give money to the translator for work done years ago, and there's potential to earn more than a fixed rate. Of course, releasing more will also increase the amount earn, since they are now paid when the chapter actually is paid by readers and not when it's submitted to Webnovel (flat rate pay). But then comes the problem, that not all books are very profitable. Some might even be a loss compared to the flat rate pay because the book just isn't popular. Hence, to not 'gamble', some people just stick to flat rate.
Privilege is in a way to give those who absolutely want to read ahead at whatever cost that option. This Privilege money earned is now split between the translator, author, and Webnovel without a need to switch to a royalty contract, so it will boost earnings for the translator during the course of the book's serialization release. The hope is that this will incentivize translators further to keep constant release rates and also build a stockpile.