I think the point Jay was making is that the situation with Protonmail hasn’t changed since the topic you linked was created. They still have hard limits on their lower plans, and they state explicitly that they aren’t designed to carry transactional email. GMail has a similar limitation, that’s why neither appears on list of recommended email providers.
ProtonMail is currently not designed for high volume sending such as marketing blasts and transactional emails
If the situation had changed then sure, it would warrant a new topic. As it stands this is just a duplicate of what was discussed three years ago.