Questions about email warm-up tools and setup best practices

You never use the original E-Mail for the outbound, you always buy "burner Domains" and "Burner E-Mail"

For myself I set up everything via Microsoft Outlook and then let my E-Mail addresses warm up on Smartlead, is this correct?

I read a lot about using aerosend, hypertide etc. for the infrastrucur. I dont understand what the usecase for those tools are, could someone please explain that to me? Is it just to setup domains and e-mails on a higher scale than doing everything manually via outlook?