When are people that engage with the website
When encouraging engagement like anything there are always benefits and consequences. Some of these benefits are people that engage with the website and posts will most likely share it with their friends. Also likes, shares and comments on a photo will appear on the newsfeed of the friends of the person that commented which spreads it further. Plus the higher the engagement, the higher the potential for increase in website visits and sales. Therefore benefitting the company. Although some of the consequences of encouraging engagement are that people may post negative reviews on the wall, or on recent posts which might deter people from commenting or liking.
Also if there is a lot of engagement on one post, people may hide the post from their timeline or unlike the page to stop the notifications if they had commented on it earlier.