early versions of the EoL website had a complexity slider which allowed users to change the presentation of the article from simple (common names, less information) to complex (scientific names, more details), which seemed like a very interesting and innovative way of dealing with the diversity of user expectations. I work on another educational project (Wikipedia) and this feature is occasionally mentioned in discussions as an interesting approach to serving both users who want easily accessible content and those who want more advanced information.
However, it seems the feature was removed after a relatively short time (archive.org snapshots suggest some time around 2010). I realise it is a bit of a stretch to ask for information on website changes a decade after they happened, but I would be very grateful if you could give me any pointers on why this was decided (was it hard on authors? not useful for readers?) or who might know more about this.