Why are email pitches so bad?

Via Twitter:

Recently my co-founder left Tintri. Now his email address has been aliased to me. Along with our interim CEO's email address. So now I get about 2.5x as much founder/CTO/executive-directed spam. Mainly it goes to my spam folder. The vast majority is:

Somebody who wants to sell me a product or service I'm not even remotely in charge of: insurance, HVAC, loans, or capital investments
Outsourcing companies who insist that their engineers are uniquely qualified to help Tintri with X, whether or not we are actually doing any X.
Technical and executive recruiters who want to sell me their candidates or services

Are these pitches successful? Or, like all spammers, are they low-cost enough that they don't have to be successful? I imagine buying the list containing my email address was not free, so there's at least some cost.

The recruiters are the most personalized; they'll generally at least fill in a role we have listed.

The first two categories have switched to a multi-email approach, using a common pattern:

Asking for a phone call, never an email or giving me a link to follow. This will never work (see Bridget above): "If you’re interested in a X, I’d be happy to discuss more on a quick call. Are you open next Wednesday?"
Follow up asking if perhaps they got the wrong person (duh) or if I didn't see the first email, and "could I direct them to the right person?" I can't decide whether it's more annoying for them to ask me to do the lead gen work for them, or if they skip this step and just reiterate their first request.
Passive-aggressive third email either asking for a one-letter response from a menu or "apologizing" for their persistence. e.g., "I guess now's not the right time."

I don't understand why spray-and-pray is still the industry default. Like I said, they mainly end up in spam.