Although the feature was introduced, it was never fully embraced by users in the same way it has been on the other social networking sites. There was never a real attempt by Facebook to encourage users to use the feature.
SO, SHOULD YOU USE HASHTAGS ON FACEBOOK?
A simple no. Hashtags have been shown to reduce interactions across Facebook. This negative effect is intensified when some pages decide to use multiple hashtags in the middle of text, making their status incoherent. When it comes to communicating effeictively and connecting on Facebook, hashtags are certainly not of benifit.
Further proof of this can be seen by Facebook themselves, they don’t include hashtags in their official Facebook page posts. If Facebook are not investing in it or using it themselves, then it is probably worth leaving the hashtags to Twitter and Instagram.