The role of the developer starter is consistency.

C41 is a standardized, replenished process. The starter takes brand new developer and seasons it so that it works the same as developer that has been used and replenished for 2 or 200 rolls.

Unseasoned fresh developer can be "too good" to meet the standard.

That doesn't mean unusable films, just that development might go too far, giving your film a little "push" or some such issue.