Once a filesystem became readonly because of the underlying blockdevice was unavailable, why can it not be remounted to readwritable?

Issue

• Once a filesystem became readonly because of the underlying blockdevice was unavailable, why can it not be remounted to readwritable?
• I had a power outage in data center, for many virtual machines the storage became unavailable, filesystems turned readonly. When the power came back, also the storage devices became readwritable again. Yet I am not able to remount them.