I would be astonished if Lightroom was the most used photo editing application, period.
Unless you add a qualifier like - most used photo editing application by people that ..........
....are invited to do educational seminars on CreativeLive.com,every week, 52 weeks a year
.....Speak at huge photo conventions, like WPPA
.....give seminars, talks, and lectures at PPA events across the United States
.....have large YouTube channels with hundreds of thousands of loyal subscribers
.....have a mindset that revolves around the twenty-teens,and are not ostalgiac for the 1990's
There is MUCH, much more to Lightroom than the "development engine" aspect that the one poster constantly references in attempt to disparage Lightroom or to cast doubt on the app. What about Lightroom presets? What about the adjustment brush tools Lightroom has? What about the actual on-screen windows and interface options that LR has, and that each individual user can custom-tailor?
What about the sheer speed, ease, and efficiency that LR is built around and geared toward? I used Photoshop since version 2.5 in the late 1990's...I "got into ACR" and automated image batch processing in 2007, and even bought "THE book" about ACR....I got the British fellow's software and used Automator software to record multi-step processes, so I could automatedly do complex import and adjustment and re-sizing routines using Photoshop: using routines I built myself, or borrowed from other Automator users.
But...once in 2012 I got Lightroom, within weeks, I was avoiding Photoshop's work flow ideas, and the PS app itself, for weeks at a time. Both apps are made by Adobe. I do not understand this continued denial of how fantastic Lightroom has become, and what it can do for actual "photographers".