In my mind, you're actually touching on a different issue.

I'd argue it's situational. The issue isn't whether a soap company can/should email you weekly (or a whether a daycare can email you 10 times per day).

The key is to make sure every contact with a customer is purposeful and provides value.

I bet there's a way for a soap brand to email you every day and provide meaningful value. Conversely, there's a way for a soap company to email you once per year and have it feel like excessive SPAM.

This is why great marketers who understand how to nurture people are so valuable. A great marketer should be able to devise a nurturing campaign that lets you stay in front of customers without them resenting you for it.

(Note: Lots of marketers aren't great, which is why lots of corporate emails feel like SPAM.)