The theory behind it is that one should expose themselves to counter-arguments allowing their claims to be attacked so they that have a chance to substantiate them or reject them upon realising they are mistaken.

You should balance this theory with the fact that your time has a non-zero value. The modified theory is that one should sometimes expose themselves to high-quality counter-arguments, etc.

The modified theory does not support online discussions too much.

It may help to realize that while protecting yourself from counter-arguments is stupid, trying to do the exact opposite by exposing yourself to counter-arguments of any quality at any time is also kind of stupid. Therefore don't feel guilty if you stop doing this. If you want counter-arguments, it is enough to ask reasonable people to provide you (hyperlinks to) best counter-arguments.

Also, absence of convincing counter-arguments is evidence for your arguments, therefore focusing too much on falsifying them is irrational. (Unless the value of given information is so high that it is worth wasting so much time for such little chance of update.)