We have had a lot of discussions about having a WhatsApp/Telegram group. Some points here:
Again, any club is only as active as its members. Most of us haven’t used our equipment in a while because of the rains(some of us have even had our equipments flooded - please see the old posts) and this reflects on the number of posts you are seeing.
Our star parties are kicking off again this month-end as the pandemic and the weather have started to improve, and hopefully, we should have more events as COVID-19 starts to decline.
Then let’s create some group in it so that we could share some pics or clear some doubts
You could do the same in the forum as well 
With WhatsApp(or the Facebook group that we used to have before), we had the exact same question being posted multiple times a week. Moderating the group itself becomes a demanding job which is not something a volunteer driven organisation is supposed to be.
The counter is that it could fragment the group between the forum & whatsapp.
A more important point is that, knowledge on WhatsApp eventually disappears. What I mean by that is, if I make a long reply about how to choose a camera for planetary astrophotography with a given setup, a month or two down the line, that reply more or less disappears.
People usually do not search for something in WhatsApp and there’s no easy way to share something again(unless I go and reply to that message with a . or something). If I had used some media to illustrate my explanation, there’s a good chance it goes missing as well if I delete it from my phone. As a result, you will either have an unclear answer or no answer if whoever has replied doesn’t see the new message.
Another point is that, WhatsApp replies gradually but definitely lose their quality over time. Having something like a forum makes people to be more precise and accurate with their replies.
Having said that, I am not against having a group itself. We do have a group that we mostly use for coordinating events and stuff. If you are interested in joining it, please DM(do not reply as a comment here, we moderate private information) me your number and I shall add you.