When it comes to the internet, features for big services com and go. During Marissa Mayer's time at the helm of Yahoo, new purchases were made and closed existing products. It is just part of doing business - deciding what is being used and what is worth shuttering.
Google has been going through its own shuttering process, most notably Google Fiber. This week, YouTube has announced that we will soon see some of their offerings go away. First to be cut is the web-based editing feature. As it turns out, less than 0.1% of all YouTube creators were using the web-based editing product, a feature which as been around since 2010, but even I was unaware existed. It's important to note that the trimming capabilities of "Enhancements" will remain.
The slideshow feature, another one I was unaware existed, but explains why there are so many identical looking slideshows on YouTube, will hit the cutting room floor, as well. Since slideshows have seen waning interest in general in recent years, a win for me as I have always hated slideshows, it makes sense for the company to end support for the slideshow composer.
Both offerings will be removed on September 20, 2017. Make sure to finish any projects that are in-progress before the services go away for good.