Ford used to say that "Quality is Job #1"
It's a good approach, despite your viewpoint on Ford's quality control (which, even as a Ford fan, probably wasn't ranked #1).
As a company leader, recruiting quality is job #1. Your success is your team's success. Your team's failures are your failures. (See what I did there, they're not actually the same, but that's probably another blog post.)
There is nothing that I take more seriously than recruiting. Even as we are currently hiring 10 (ten!) positions, we must maintain our standards and our approach. It's slow and hard, but that's OK.
In addition to zero turnover, we're 5/5 on reviews at Glassdoor. This has given us a huge pipeline. With our current roles we are receiving hundreds of basically qualified applications per month. Given the volume, we have to focus in on screening.
I've been surprised at how little effort can go into applications. On one hand, I understand that if you are applying for a lot of jobs, you probably don't want to put in the effort to fully customize. If you're a developer, this is a bit more acceptable where you don't have a cover letter, etc.
If you're on the business side, the cover letter can make a big difference. After a quick scan of the resume, a cover letter can be a huge differentiator. It doesn't have to be long or detailed. It cannot be a form. Submitting a form letter is as good as not submitting anything (that is, it's not good).
A cover letter is your opportunity to tell the hiring manager why you are different than the hundreds of others. Maybe it's that you are a fan of what we do. Maybe you want to change your commute. Maybe your job titles aren't perfect, but you think you have key skills that line up.
At one level, we'd like to resumes that do this on their own, but because we do accept cover letters, you have an additional opportunity to tell us more. Take it.
When I have 100 resumes for a single role, simply having a cover letter may get you to step two in the process. Having a cover letter that shows me you did even five minutes of research instead of just clicking "apply" on everything you saw on indeed.com will go even further.
There are absolutely occasions on daily basis where a cover letter gets an applicant to the phone screen where the resume would not. That's the take-away here. We read every application and we take hiring seriously, because it is the most important thing we can do in setting up the team.