There's a worrying trend where people are just repeating this statement or variations of it:

• Get links from high quality domains
• Get links from relevant domains

Often these two statements are used together/in one. Both are completely wrong.

TL;DR Updated

There's a concept that getting backlinks (vs buying) from sites that have "low authority" = damaging to your site - they are not.

Spammy sites <> Link Spam (the act of buying or exchanging backlinks) to manipulate search results.

DA and PageRank

DA is not entirely meaningless - its an estimate of PageRank. It might not be accurate but its the best we have. Its definitely used by SEOs

Background

Firstly, lets assume people dont have access to any domain with massive DA levels- because that is the actual, real world situation. If you have untethered access to so called "high DA" sites, then you are talking about buying links or shopping for links and trying to "avoid detection" or getting the best value for money.

As this isn't a marketplace and the vast majority of new posters here are not buying and do not have access to links, I'd like to set the stage for discussing this in a real world setting.

Firstly - low DA sites DO NOT intrinsically add harm.

My own domain has a DA score of 16 - or whatever, I dont care, it doesn't matter to me. But me linking ou doesnt do any harm. Actually, I could help any domain rank for any phrase related to SEO, NYC, SE Rank position, Florida, etc

Real World Scenario

Lets say that there are two local IT companies. One provides cloud SaaS services and the other provides local IT hardware support. Both target their local area.

They both aren't SEO providers or web developers. In conjunction with their web design / marketing agency, they build a go to market offer and write a blog post outlining their special offer to help local businesses migrate to the cloud

Both sites have a estimated PageRank/DA of 5 and get about 1000 visits each.

How is cross linking between those two sites bad?

PageRank is cumulative: Big domains are built from low-DA

Big "DA" sites get their "DA" from cumulatively collecting DA from small sites. DA starts at 1 - so low DA literally cannot "HURT" or HARM sites