Earlier quoted context omitted.
I think it's a sane practice to keep the marketing landing page on a separate domain than the product in case of SaaS.
Why? I always get frustrated when I end up in some parallel universe of a website (like support or marketing) and I can't easily click back to the main site.
The technical perspective is that things like wildcard subdomains (e.g. to support yourcustomername.example.com), or DNSSec if your compliance requires it, etc. cause an extra burden if done for these two use-cases at a time.
> can't easily click
Http pages don't have problems with having a link to example.net from within example.com. Or the opposite. Seems like an unrelated problem.