The problem with competitions that have a relatively low average quality, is that the revenue is relatively less too. That is, you get low money prizes. This affects your ability to purchase players in the following season, especially if you intend to purchase some fast, 5-star trainers. Money is a significant limitation in the low and middle levels. While you might have a better chance of progressing in the later rounds when the level is low, a few rounds in a significantly higher level competition might earn your team more money than the addition of all the money prizes for most of rounds of the lower quality one.