And Yugoslavia were twice the 4th best team in the world (two world cup semi finals) and twice the 2nd best team in Europe reaching the european championship final twice.
Croatia, Bosnia, Serbia and Slovenia have all played at major tournaments and North Macedonia will be at Euro 2020 this summer.
Montenegro reached the playoffs for Euro 2012 losing out to another supposedly 'fairly new' country the Czech Republic
Kosovo reached the playoffs for Euro 2020 losing out to North Macedonia.
That part of the world has a proven record in international sport.
Frankly its lazy and patronising to label any of the former eastern block countries as not good enough for international football.
7 world cups and 7 european championships since the break up of the USSR, Yugoslavia, and Czechoslovakia . With the exception of Montenegro (2006) and Kosovo (2013) none of the countries from the eastern block are 'fairly new' to International Football