Hello!
I'm not familiar with Czech rules, but this is the way IFR flying is going in the UK, and presumably worldwide.
In ECAC airspace B-RNAV capability requirements were introduced in 1998. That is
thirteen years ago (see:
EUROCONTROL Navigation Domain - B-RNAV ). The Czech Republic joined the ECAC states in 1991, therefore the B-RNAV requirement was introduced there in 1998 as well.