I find that a lot of good information gets lost in threads with very long posts, as the information is not necessarily in those posts.(This is not equivalent to saying those long posts are not useful).
To make the forum easier to navigate, I suggest that only the first four lines of text are shown and if the post is longer, a read more button is displayed.
I wouldn’t support that suggestion … Having to expand all abbreviated posts would be a tedious process, with likelihood that important information would be too easily overlooked/missed.
I did consider that too. On the other hand a few lines could be enough to tell someone scrolling if they need to read the rest. Like most sites that have long texts and provide you with a page containing summaries.
The option to enable or disable the functionality can also be tied to a setting in the account preferences and/or toggle switches in threads.
Getting an abstract of long posts would be nice…suppose we have to wait for some real or artificial intelligence summarizing the tapeworms.
Until then, authors are well advised to write short posts instead 
Yes, meaning when people write here and want others to read, they’d have to bring their point across early on and elaborate after. I think I will use…
… this option in future should I ever feel the desire to write a longer post here again.