What LO probably also helped is the relatively substantial home market (Poland has 38m inhabitants and ranks 21st for GDP globally). Together with the also substantial diaspora, in particular in the US, this helped to generate a solid O/D demand.
Meahwhile, Romania, the Czech Republic and Hungary are less than half the size and all the other countries in the region are even much smaller. Ukraine is almost the same pupulation like Poland but is economically much smaller. So Poland really stands, both in terms of population and economy.