Especially with the rise of "ghost postings" so quantity over quality is greater than ever these days
I think cover letters are still absolutely relevant to the job process.
I liken cover letters to cheat sheets that you prepare for an exam. You may not need to make one to be successful, but can be very helpful.
Usually with cover letters, I try to make the argument that I'm good for the company, and the company is good for me. This usually allows me to frame the way I look a new job as a business agreement where both parties can benefit, and that I'm not a parasite taking from them and not giving.
I don't make cover letters for each and every position I apply to or look into, but for those ones i think I have a good chance of landing and those companies I believe in, I'll absolutely put in more effort with cover letters.