This maybe not the proper forum but since this is still somehow a question concerning private servers, i decided to post it here:

Some server say I have to update the clean install of gracia client first and then edit the hosts file but I am still able to connect to them and play just by simply editing the hosts file and playing straight away.

So what's the point of updating the client then if I can still play without updating the client?

By running the official updater it means you will always have the latest client files. If you are using a patch method then more often than not you never have the latest client files as server owners needs to update their patches clients.

In some of the servers you can have errors imo,btw i never update it

Sure you can play on servers with different client versions, but you may have issues yourself.

Look it this way... let's say you have a client you didn't update before the Eva's Inferno event. And the server (such as lineageuniverse) has already updated to include all the new items (watermellon hat, etc). You either may not see those items, or you may crash if someone wearing one is in range of you.

There are also other errors. Like a protocol 83 client when sending a linked item through chat can't send it properly to protocol 87 clients. It comes out as giberish and not a real link.

There's also known party issues with older clients as well.

Trust me, it's best to keep updated. Not gonna kill you really. Besides, on good servers, you get access to all the new items and headgears with the newer clients.