Some of my badges are still locked even though I achieved them.

I completed a few achievements but some still show as locked. Does Chess.com take time to update badges or is this a bug?

It's a bug. I believe if you contact support, they'll unlock them for you.

Good luck.

It depends. Some achievements are no longer available and some are ones staff can't do anything with. I also think they may gave stopped unlocking any.

If some achievements aren’t able to be unlocked, then what’s the point of them being there?

Do to changes in back end code, the triggers apparently don't happen, and don't get awarded. Staff have no capability, to unlock some of them (mainly the milestone one I think)

As to why they aren't removed, I'm not sure. I know there are plans for a project that will likely impact achievements, and it's likely that rather than take developer time to remove existing achievements, the mats being saved for future updates.