I’m not sure, if I understood the question 100% correctly, but I will try to explain.
Imbalance of factions has always been a problem. There are several factors. The most important is probably the low number of players in the game overall and them being spread out over many campaigns. When there aren’t enough players at any given time to fill a team in a match, then the game will fill the remaining player slots with bots, to reduce waiting time. Bots are pretty weak. While individual skill matters a lot, and sometimes even a single player can carry a team to victory, those teams with fewer bot players in it, always have a distinctt advantage. So, popular or trending factions are stronger overall.
But what makes a faction popular? Again, many factors:
- Factions are more or less popular depending on the time of day, probably because some countries or regions of the world have preferences for certain factions. For example, when it’s evening in Russia, expect more Soviet players.
- Imbalance of faction equipment. When a certain faction is perceived as being stronger, then players, who only care about winning, will prefer to play those.
- When an update adds new levels to a campaign, then the faction with the more interesting toys gets played more. For example, in a past update Axis in Normandy got the Panther and Allies got the M10. Panther is clearly better and also more iconic. So those players, who had already unlocked everything else in these factions before, tended to grind Axis first and Axis was the stronger team for a while, until they all got their Panther.
Once a faction becomes popular enough, there is a kind of “tipping point” and the imbalance of players gets worse very quickly. This faction is now trending.
At first, only the opportunists and eternal noobs will stop playing the weaker faction and switch sides or go to another campaign. The losing side will start losing harder. Now the more determined players start playing that faction less and it gets even harder. By the end even the nomads and hardcore fans of that faction will be frustrated enough and leave. Only bots and total newbies will be left.
Nowadays, we have another factor, that contributes a lot to the trend problem:
The frequency of events, in which players have to reach a certain amount of battle points per day. Many players, who have nothing else to grind anymore and are only interested in the event rewards, or aren’t really in the mood to play, but also don’t want to miss out on the time-limited rewards, will want to get done grinding the battle points as quickly and easily as possible. Therefore they play a trending faction, where they can mow down a large number of bots.
But trends can easily come to a sudden end. This can be the result of an update or a large number of veterans being done grinding the trending fashion. Unfortunately, trends don’t just usually end, but they reverse instead. Right now for example, Allies in Tunisia are totally dominating. Only a month or so ago, the situation was the opposite and Axis were dominating almost as hard.
The coming merge of campaigns is supposed to take care of this problem. The rationale is, that even when there is some imbalance in the popularity of a faction, that there will still be enough players, so that bots should become a rare sight. But the OP is concerned, that players will then be spread out over several battle ratings instead of over several campaigns. And so a faction may dominate in low and mid BR for example, but get stomped in high BR.
This is my understanding of the situation.
I myself am also a nomad by your definition. I play every campaign except for Stalingrad and Pacific and I play every side pretty much evenly. But even I only continue to play Axis Tunisia, because I am close to unlocking the GranatbĂĽchse and I suspect it will become useful after the merge. It is a miserable slog and I only play them with XP boosters.