It shouldn't take an hour to write a decent cover letter, and there are many ways you can learn about the company you're applying to. Starting with the job posting, but LinkedIn and their "about us" page would be a couple more low effort ways. When someone is able to do these things and write a decent introductory letter it's a strong sign that they will also be able to deal well with challenges that come up in the course of work. Plus, as is its purpose, it gives you a chance to describe why you're a good choice for this specific role, and to address any apparent deficiencies in your skills or experience.
That isn't to say that the lack of a cover letter is disqualifying (though a bad one might be), but a good one can definitely set you apart.
That isn't to say that the lack of a cover letter is disqualifying (though a bad one might be), but a good one can definitely set you apart.