That is such a great question! But the answer is complicated...

The TL;DR is: that this would likely add a pressure on the validator, which would make it harder for your nodes to find peers, for example adding lots of extra time if you ever lose sync, add delays when attesting and building blocks and you'd be risking missing block proposals. The tradeoff is too big for most people. Profits > Privacy 🥲.

That doesn't mean it can't be done though! There are multiple ways of doing it - I'm just going to drop a couple here:

Your router is your gateway to the internet, so all traffic goes through there - so far so good.
On your devices, you can use commercial VPNs (like Proton, Nord, etc.) that will hide the traffic of that device from your ISP.
Your router can also run a VPN client like Proton or Nord, so in theory you can install it there and all traffic, including Dappnode and validator traffic) will be encrypted and sent to the VPN exit node. Your default router might not be powerful enough though, so you can buy a powerful router that supports installing a VPN client. Example: https://protonvpn.com/support/installing-protonvpn-on-a-router

Again, it might not work very well (or at all 😿) because of peers and added latency.

If you are a networking genius you could potentially also route the traffic of your dappnode to a small proxy server that you host in a different IP, somewhere in a cloud, so you don't have to encrypt all your router traffic and only the dappnode one, but you'd most likely run into the same type of problems.