I mean, in theory, yes, but I mean, I'm sure you've seen your share of mishaps, right? Like when companies send "Dear $CUSTOMER..."? When something that blatantly obvious can get through, what confidence do you have that training is enough to prevent more subtle things like this for all eternity?
I have a paper letter here from my dentist, the purpose of which is to explain that they've cancelled all routine appointments, because duh, of course they have.
The letter addresses me as "Mr" in some places and as "MrNicholas" (no space) in other places. But to be fair it also claims the problem is COVID-9 (not COVID-19) so I'm guessing that correctness was not the number one focus of the person typing it.
We had some employees working from a coworking space last year, and we would receive invoices from The coworking biz addressed to "MR Company Name". They would frequently omit our VAT number as well. Of course, we could not pay those invoices, and whenever we got in contact with their support The response would be so delayed that we already had received multiple warnings and threats from their automatic invoicing system. They did eventually get their shit together and voided all The junk invoices they had sent us, but it took three months or so... And this was a huge player in coworking, not a small indie bussiness.
Mail merge is mail merge, be it, to an email, letter or text.
Dental practices aren't usually big enough to have a person who devotes such a large percentage of their time to composing mail merge templates as to become slick at the task. Rather than being sarcastic you would be better being grateful that they were courteous enough to go to the bother and expense of writing to you at a time when their business was experiencing complete shutdown and they themselves were facing total loss of income. They probably had more on their mind than pleasing pedants who'd focus on trivia at a time like this.
Did it come across as sarcastic? I certainly didn't intend that, of course they have more important things to worry about. They'd usually come in to do a day's work and now suddenly everything is closed and they've got to write this weird open-ended letter.
It's an NHS dentist, so unless we have millions of deaths I expect the practice will continue to exist and receive funding as before. Such practices are funded partially on the basis of the number of patients who are notionally "theirs" to look after and that hasn't changed even if providing non-emergency services is not a priority now.