The self-admission is the disposition of the litigant's procedural rights, and may have a substantive impact on the fact-finding and the burden of proof.
A Chinese court can investigate, collect, and preserve the evidence ex officio or upon the application of the parties, when the evidence may be destroyed or difficult to be collected in the future.
"The burden of proof lies with the party asserting a proposition" (谁主张,谁举证) is a primary rule in the judicial proceedings. The application for evidence collection by the court can only serve as a complement to the presentation of evidence by the parties themselves, and it does not work all the time.