Leverkusen and Borussia Dortmund use the same logical measure, because they do the same thing: they take players, transform them into quality players and then don't aim to build a squad capable of aiming for the title, but always tend to sell these players, being more interested in revenue.
If this goal continues, it's likely that both teams will struggle to win the league title and will never pose a serious threat to other teams in leagues other than their own. I hope that this season, both teams can develop significantly and no longer focus solely on revenue by selling good players and developing other mediocre players into great ones. This is because not only is it time-consuming, it also drains their energy, which will ultimately be wasted when they prioritize selling more.
It's a money topic, plain and simple. However rich, those two cannot compete with the biggest clubs like Bayern or Madrid in terms of salaries. Players will want to get paid and thus leave. In fact I'd say targeting top young talent is the best way for BVB and Bayer - they are very attractive for that group as they offer minutes and opportunities in the BL and CL. They will make a profit to buy more top talent and once in a blue moon when all stars align they will advance to the top club tier for a season or a couple. Bayer is stuck in that position, but if BVB saved up enough to start building a new stadium they might bridge the gap to Bayern at least partly. I liked what they did now, dropping Brandt and Adeyemi to get new forwards. Now just need to sell Guirassy to complete the change
