bitcoin core – advanced electrum server that reads blk.dat files directly

Nowadays, advanced Electrum servers read the blk.dat file directly from Bitcoin Core’s blocks folder as part of creating the initial internal index. I think they try to keep the index in sync throughout its life, but I’m not sure about that.

First, I read here that it’s a bad practice for technical reasons.

Bitcoin Core also ensures that those files are only readable by its own users. So the only solution I’ve found to sync those Electrum servers is to run them as the same user. It seems a bit awkward to give permission to such software to modify block files.

I’m a little worried about this. Many projects require an index of these Bitcoin addresses, so most seem to accept the compromise. In my opinion, the best option is for the Electrum server not to use that file. But the reality we have to live with is that they do what we say.

The best solution might be for the Electrum server to stick to RPC calls, but I doubt that will happen for performance reasons. So why doesn’t Bitcoin Core include a configuration switch to at least allow read-only access to those files?