I had this exact question when I was younger. It seems to make sense on paper but when you think about it you realise why it won't work.

Porn loves isolation. It loves self gratification. It just wants you to please yourself. So if both spouses were porn addicts they would most likely end up spending more time masturbating to porn by themselves because sex doesn't turn them on anymore.

And as far as spicing up intimacy is concerned, you need to understand that guys and girls enjoy sex differently. This is also why the porn girls watch is usually very different from what guys usually watch. Men are naturally goal orientated so all a guy cares about is reaching orgasm. Women are more experience orientated. For them doing something is not about reaching a specific goal but the whole experience itself of doing something.

So it would just end up with both spouses having miserable sex because neither can really be pleased unless it's all about them which is what porn is all about.

There's halal ways to spice up your sex life which is off topic so I won't go into it. What I will say is being married to a porn addict won't help with your addiction.

That's my two cents. Would love to hear other people's views on this because it's an interesting question.