That’s precisely why there is a vote limit 
The idea is that people are conscious about the votes scarcity and will spend those wisely. If a higher priority item shows up, they will need to remove a vote from a lower priority item to spend it on the new high priority one.
Adding more votes every day would effectively turn it limit-less and dilute the signal of votes, making it worthless as an information source for projects. And you can also accomplish the same end-goal by increasing voting_tl3_vote_limit proportionally to your desired backlog size.