Bayern was really not that dominant but there was no team ready to make use of that. Dortmund was a joke at the end of the season, it was unbelievable what they did and also didn't deserve it then.
Leipzig is consistent yes, but it's never enough for them to lead the table and stay there. They are among the top four and that has been like that for quite long I think, but they could never be a threat to Bayern Munich in the race for the Bundesliga title. For 5 years in a row they finished in the Champions League qualifiers, but every time it was quite the distance to Bayern Munich.
It's difficult when the difference is so stark in terms of mentality and strength that even when there is an opportunity, it sometimes seems to be wasted.
For example, last season where it should have been easily obtained by Dortmund because of the determination they only had to win 3 points when they were quite favoured but in the end everything returned to belong to Bayern, which is irrefutable evidence that clubs other than Bayern in the Bundesliga seem to lose hope in the title race.
Leipzig in terms of performance I would not say they are stable but they can always be in the top 4 at the end of the season.
The start of this season they did better than before but I agree with you that it won't be a reference point for the title race because in the end all they're after is probably the top 4.
Stability is relative. If a team constantly ranks among the top 4 teams, in my opinion that is called stability over a long period of time. I am not so much talking about a month or two because that's when Leipzig does have problems from to time and that is the reason they are not playing for the title, but only for rank 2 to rank 4. Bayern is stable for over a decade now as they always won the title, but if you take a point in time or a time window like the end of last season, there was instability. Now it needs someone to punish that and this is where the Bundesliga has a big problem.
Bayern did not win 13 games last season, they did not win 13 out of 34. That has not happened in over a decade and now that it happened, Dortmund could still not win it because they are not consistently in the 70+ points range.