No they aren't. You can choose to buy refundable business fares, much as you can buy refundable economy fares. But the default is non-refundable tickets with hundreds of dollars high change fees.
Some business travellers do buy mostly refundable tickets, but they specifically have to select them regardless of class of travel. Tickets bought on day of travel also tend to be refundable since that's often the only fare that can be sold close to departure.
Yes, but if you're keeping the ticket active so you can access the lounge, you have that several thousand dollars still tied up in the ticket. You could just buy a yearly pass for a small fraction of that, so it makes no sense.
Since most - if not all - airport lounges are behind security, you'd still need a valid boarding pass (and thus a ticket) to be able to reach them. And even if you don't, most lounges require that you present a boarding pass for same day travel together with your paid membership card to get access.
In this case, I assume the goal was to eventually cancel and fully refund the dollars in the ticket so that all lounge access could be had for free.
Some business travellers do buy mostly refundable tickets, but they specifically have to select them regardless of class of travel. Tickets bought on day of travel also tend to be refundable since that's often the only fare that can be sold close to departure.