There's no doubt that the blogging platform, Blogger.com is a great way to easily create free blogs. If you're a budding author and want to test the water, it's an ideal platform to hop on. The trouble is, blogging "blogspot" subdomains are all too frequently used by spammers that are looking to increase the domain authority of their own (or their client's) website/domain.
If you're in the SEO (Search Engine Optimization) game, then you'll already know that getting good quality, organic backlinks that will give your website a boost in the rankings is hard work. It takes a lot of time, effort and networking to find the right kind of sites to deal with. An even slower and harder route (but still the best and safest) is to write killer, interesting content that other webmasters will naturally want to link to in the future.
Google's mantra of "Content Is King" still holds true.
Alternatively, some SEOs prefer to buy backlinks to take a shortcut. Whilst paid links aren't inherently bad, they can be a risky strategy. If you do go down this route, it's imperative that they are good quality, human-reviewed websites that only accept real and authentic websites to link to. If they're not, and you add your site, you may end up part of the "bad neighborhood" that that particular website is associated with. This can end up actually hurting your rankings, not improving them.
Since Google clamped down hard in recent years with its Penguin algorithm, acquiring dodgy backlinks from spammy websites such as fake Blogspot ones became a real issue and severely damaged a lot of websites that fell prey to Google's new strategy.
If you check the backlink profile of some websites with a high DA (Domain Authority), you'll see that they have a lot of these types of links in order to feign their own DA and create a false impression to try and fake genuine backlinks. This isn't a problem if you've done it and are still getting away with avoiding a Google penalty. If you see in a website's backlink profile lots of subdomain that look something like this: somewordsorrandomletters.blogspot.com then you should consider coming up with a better plan for your own website.
The problem is, if Google's Penguin algorithm catches up with these questionable tactics and it penalizes your website, it can be tough to recover. It's a "guilt by association" scenario if you have a lot of these types of Blogspot subdomains linking to your site and it will inevitably take time and effort to undo the practice that was previously successful up to that point.
Don't do it!
If you're thinking of doing this yourself, I'd advise against it; it's simply not worth the risk. Similarly, if you're one of those sorts who prefers to buy links instead from companies that advertise cheaper backlinks such as "50 backlinks from DA40+ websites for $15" you'd be well advised to scrutinize the backlink profile of their so-called "high DA" websites.
The likelihood is that that they run a PBN (Private Blogging Network) of their own, quite probably using a network of free Blogspot subdomains with low-quality content with plenty of keyword stuffing to build a fake Domain Authority.
If it sounds too good to be true it probably is.