Plesk documentation is stated that Plesk on Virtuozzo 7 supports all resource limits (Plesk Documentation and Help Portal).
This is Plesk documentation bug with ID #PTD-1206 which is planned to be fixed in the future.
Plesk on Virtuozzo 7 does not support disk I/O bandwidth (
blkio). As a workaround, install Plesk on a dedicated server.