I am not sure how many words are "too much" but most posting platforms explicitly limit the posting characters for a few reasons. One of those reasons being the impact of a post. A post should not be reliant on the total amount of the content, but the quality of the content published. Take a look at your local newspaper for example, each category has a set number of columns that can be written in and the columnist must make his piece as impactful as they can within those limits.