I think being a fan already makes you subjective to a degree and sometimes it's hard not to be biased. No need to argue, I wouldn't call this arguing but rather discussing. To address some of your points.
Population number was not an excuse but a fact to present the numbers game. You already partly answered what they should represent yourself. We have to look only at those that engage in the sport. Now I don't have the number of active players in Slovenia, Poland or Russia. I can tell you however that in Slovenia there are 114 club registered at the Volleyball Federation of Slovenia (Slovenska odbojkarska zveza), There are 497 in Poland at the Polish Volleyball Federation (Polski Związek Piłki Siatkowej) and I couldn't find the latest Russian numbers. I checked the site of Volleyball Federation of Russia (Всероссийская Федерация Волейбола) but my russian is not at a level that would let me research that much further. The report I found was from season 2014/2015 but didn't refer the number of registered clubs or players. However, going after the trend that a higher population means more registered clubs, which consequently means more players, we can assume that Russia has even more active clubs and players. While this is no proof of any kind, and doesn't generally apply in sports, purely mathematicaly and statisticaly looking, with a higher number of players it is more likely that among those will be a higher percentage of talented players emerging. Maybe this isn't worded properly but I think it is clear what I mean.
Maybe another example to put it into perspective:
There is one Slovenian player playing in the NHL, Anze Kopitar. North America has more registered hockey players that Slovenia has inhabitants. There are 435 canadian players in the NHL out of 637.000 eligible registrated players at Canadian Hockey Association . That is 0.0683%. One slovenian player out of 180 registered players at Ice Hockey Federation of Slovenia (Hokejska zveza Slovenije) is 0.555%. I think those number speak for themself.
I thought maybe you would like this analogy because you like to stay to facts and stats.
In the end, this doesn't prove anything. That doesn't mean Slovenia has better athlets or that they are inherenthly disadvantaged in competitions.
I, personally however, think that being among top teams in Europe (currently) and being able to compete with the best in the world is a great achievement for the country and its athletes. I think it's fair to praise them for their run in the ECH.
You said yourself, North Macedonia and Slovenia both have a population of ~2M, yet Slovenia is ranked 17th by FIVB and North Macedonia 131st.
I think I already shared my thoughs on the game between the two. I'll just copy my final thought.
When it comes to stats and past achievements I have nothing to add. I agree with you, historically Slovenia's NT didn't have any visible results and major success. Although, However, I hope we can agree that the team has played well the last couple of years when compared to their previous results and has improved. I think this is Slovenia's peak performance at the moment in term of the result (not their gameplay on the court).
We might not agree on our individual and personal interpretation of a top team but I think I was careful with my choice of words. I called Slovenia's NT a top team while Poland and Rusia World class. I'm not arguing with your tier list though, quite contrary I agree with it. I'm just voicing my opinion that Slovenia's NT is deservedly in the final of ECH 2019 and looking at the most recent results can be called a top team.
With that out of the way. Let's enjoy today's game.
TBH, I am a Poland NT hater most of the time, I don't like Heynen and some of Polish players. But I do agree they are one of best teams in the world, based on the stats in world tournaments.
The basic logic is: if we say Slovenia is a top team because they beat Russia/Poland in knockout. Then how about when Slovenia lost to North Macedonia and Russia in group matches, can we say they are a bottom team? Clearly not. In this case we just say they have a good day or bad day. So what's the standard to define a top team (Class A team) and good team (Class B team)? I won't use I feel, I think, I sense or whatever words. I only check their NT stats, esp stats in Olympics, WCH and WC. Hard evidence talks, just like we evaluate a player by his stats in the whole season, not just by several games.
If someone said Slovenia is a top team in this ECH, I agree. But if someone said Slovenia is a top team in the world, I do not agree. A top team, by default, should be defined or checked by spanning a certain period of time, such as a few years, to make it more convincing. Just my 2 cents.