One could do some searches, to get answers to this, below is from the first hits on my search, it may be just more gossip, or FUD, but based on what it says, Debian LTS was started before systemd came into the picture ,Please let us all know when and why Debian LTS was started.
http://www.linux-magazine.com/Issues/20 ... Debian-LTS
But it is better to read the entire article, this is just a small piece.
=== additional===Despite its reputation as an all-free, counter-cultural collection for hackers, Debian is also quite stable and reliable, which makes it a viable option for many corporate networks. But after many years of Linux in the enterprise, admins have a pretty clear idea of what they want: a system that will operate for several years without requiring an upgrade. Rolling out a new operating system in the enterprise can take many months, and the process is quite complex and prone to complications. Better to make such events as infrequent as possible.
In 2014, the Debian developers woke up and realized the recent trend for Long-Term-Support (LTS) releases had left them behind. Because Debian is not backed by a company that can make money on selling support contracts (like SUSE, Red Hat, and Canonical), they had never gotten around to implementing some form of long-term support.
To get a first hand report as to why Debian LTS was started, perhaps one should ask Raphaël Hertzog, or some of the others involved it starting it.After completing the preparatory work, the then-current Debian 6 "Squeeze" became Debian's first LTS version. Its successor, Debian 7, has a correspondingly long support period: "Wheezy" was released in Spring 2013, and its support does not end until 31 May 2018. Currently, Debian is planning to offer Debian LTS support for the still-current Debian 8 "Jessie." The same applies to Debian 9 "Stretch," which will probably ship in the spring of 2017.
The infrastructure for handling LTS tasks is provided by Freexian , a consulting company operated by French Debian Developer Raphaël Hertzog. Hertzog publishes a monthly report on the current status, the tasks taken, and the hours worked by the individual developers. Any developer who receives money for work on Debian LTS is required to submit a report on a monthly basis.
The first official paid work for Debian LTS  was completed in July 2014. The report published at the time  showed 21 hours for two developers; the following month, the two developers had already contributed 32 hours. Two years later, in September 2016, the figures grew to 152 hours provided by 13 developers .