Backlinks as a Digital Marketing company?

So what we're all after - as SEO/online marketing specialists. Are backlinks from same-niche websites right?

Does this still hold true for DM (digital marketing) websites/businesses though?

Have you ever heard of one DM business backlinking to a competing business? Outside of Gary Vee or Neil Patel maybe?

None of my Google ranking competitors link to each other, or have DM websites backlinking to them.

Which kind of backlinks does your business rely on to rank on Google?