Learning a programming language + libraries and API's required for browser automation is not time efficient if all you want to do is build some seo bots for backlinks.
The reason you buy programs like zennoposter is not 'because automation cannot be done otherwise', it's because it saves you months of time.
If you want to make complicated bots for a living, and apply programming in other areas as well, then yes, definitely dive into the nuts and bolts of C# so you can make the best and most unique bots and applications that suit your needs perfectly.
But if you just want to build some bots so to automate some backlinks to your website, learning C# is an insane overkill and a total waste of time.
Remember that after you mastered the language, writing code and debugging also takes large amounts of time.
It's easy to look at a coding task from afar and say 'yeah, i'll just do this and this, will take 10 minutes'. Trust me, in reality it will take 10 days. Been there, seen it, 100's of times.
You'll be spending the bulk of your time coding. While others will use zennoposter (even if it's buggy) and get the task overwith 10 times faster, and will apply their time in much more valuable areas (marketing, content, etc etc).