Some blog owners are not going to be able to provide SSL access to their blogs - even with SSL enabled.
Blog owners who prefer to use the "www" alias of "blogspot.com" - and who have chosen to enable SSL access for their blogs - report "Invalid Certificate" errors, when trying to access. And other blog owners report problems, when they have photos, hosted by Google and Picasa, using "http:".
Blog owners, who require HTTPS / SSL connectivity for their blogs, need to be patient. Impatience causes various inconveniences.
Deceptive site warnings.
Clever workarounds, to provide custom domains using SSL, are not worth the effort.
Blogs using CloudFlare will be classified as "Deceptive" sites.
Invalid certificate warnings.
An invalid certificate warning, when SSL access is attempted, is pretty scary.
Nobody can access this blog - without some extra clicks, and cautions.
Mixed content warnings.
And some blogs, which do permit easy SSL access, generate "mixed content" errors.
Most people can access this blog - but how many will want to do so?
Both the invalid certificate ("ERR_CERT-COMMON_NAME_INVALID") and the mixed content ("... it contains unencrypted elements (such as images) ...") represent blogs that won't be able to provide SSL access - and provide readers an enjoyable experience.
A blog with an invalid certificate, with SSL access attempted, won't easily provide a connection. The browser, that the would be reader is using, is not going to connect to a website with an invalid certificate, without the reader being properly cautioned.
The link to the blog is there - so you can get there, if you wish. How many would be readers will, happily, "Proceed to www.whatever.blogspot.com (unsafe)"?
And, how many would be readers will enjoy accessing a blog that contains unencrypted elements (such as images). Maybe there are no unencrypted image exploits, in the wild, right now - but how many people who care to use SSL will know that, for a fact?
SSL is available, for blogs which can provide it - but not all blogs, which can provide it, may be suitable to provide it.
An Important Update
If you did not use a Blogger / Google account when you Followed this blog, years ago, you are probably not Following now . During the past...