Depends on how you're doing it. It's common to be subscribed to multiple versions of any particular community and those cross posts will show up alongside each other in the feed.
I suspect for many it is just a convenient excuse to buy a new vehicle because they're tired of their current one and need a way to justify the cost to themselves.
A spare vehicle is legitimately useful if you have an actual use case and are fortunate enough to have the space for it. My winter car allows me to do all of my own maintenance without having to worry about stranding myself at home.
Yes, like I said compared to Google translate. Just like the reply you linked to said it outperformed it.