What do you think, is this the case?
Generally, yes, although there are examples to the contrary - very highly upvoted foot-long answers. Much depends on whether the lot of content is truly essential, or just bloat (or related and on-topic, but peripheral information).
If not, can you give me any advice
Some general rules that come to my mind:
The first thing to do is obviously see whether there is any bloat. Is there a way to express things with less words, without becoming too cryptic of course?
Sometimes it is necessary to trim legitimate content because it is simply too much to digest. Check each sentence for whether it's really necessary to answer the question.
Text formatting, headings, bullet points, and images can help make a long answer more digestible.
Adding a tl;dr summary at the top or the bottom of the answer can sometimes also be helpful.