Because it's 2022 and we all have computers in our pockets? Which also happen to have cameras? Makes it SO much easier to snap a pic at the machine of the screen or the part or whatever and upload it. It's a giant pain in the ass to send pics to yourself, download them to the pc just to re-upload to a forum.
I also read PM while on the couch, waiting in lines, on public transport, as a passenger in cars, the list goes on. I don't carry my laptop with me everywhere, but I do my phone.
Yes, I write on my computer at my desk, as I'm doing now. But I would argue the vast bulk of social media and causal computing is done on a phone or a tablet now. Forums are a form of social media.
If PM doesn't keep up with the world, it will get left behind. Plain and simple. The Instagram machining community is easily as knowledgeable and helpful as PM, and the ENTIRE thing is done on mobile. If PM wants to stay relevant, it needs to be useable and accessible to people younger than the age of 40.
Forums rely on traffic. If you don't get traffic, you don't get ad money, and the forum closes. If I owned PM I would do everything in my power to make my site as appealing to as many people as possible. Mobile computing is here to stay, so it makes ZERO sense to not consider it when doing forum upgrades.