Your arguments are usually a little more fact based than that one...
Of course a lawn is better for the environment than artificial grass. But speaking for myself, I have two dogs and a child. In our last house the result of that was that the lawn was destroyed every winter, and the child couldn't play on it anyway, because keeping it clean was impossible.
Now, it stands up easily to all the abuse the three of them can offer, can be cleaned much more easily, and if there is ever anything nasty left on it, can be hosed off, disinfected, even bleached if you really want to.
it's been down for 3 years, and still looks like brand new. I check it over for weeds and remove them every now and again, give it a brush about once a year, and run the garden vac over it occasionally.
So, in my case, it's not about convenience. It's about the difference between being able to use it or not. And the borders have plenty of flowering plants in them to make up for the lack of grass.
I've considered doing this to the front lawn too as a balance:
https://www.wildflowerlawnsandmeadows.com/product/low-flowering-lawn-plant-plug-collection/
The only thing stopping me is the conviction that I'd **** it up and kill them all.
Oh, as for the tent - you will still be able to use it, as long as your guy ropes are long enough. Just peg it out into the borders rather than through the lawn.
And last point before bed: Yes, it's a lot of plastic. But it's also got a 20 year guarantee on it, so I confidently expect to last at least that long. If you're going to use plastic for something, using it for something with that kind of longevity seems like a lesser evil.