Actually, flushing those floor drains can be awkward. They're often set in the wall, not the floor, and hidden behind a toilet, washing machine etc. So I just try to seal them with tape.
I can understand the awkwardness at some places where it is not easily accessible.
However, sealing them off with tape might not be a good idea as they are for draining in an emergency situation as not to cause water damage to the flats below.