Some of us like to be in control of our data and/or not pay others for what is essentially free. Also, I am not sure how third party email sending services can

Some of us like to be in control of our data and/or not pay others for what is essentially free. Also, I am not sure how third party email sending services can avoid having me setup a SPF record — as for the PTR record, it’s a good thing to have even if you do not plan to use the IP for sending emails.