I was just looking at that same list. I'm surprised Lua is that low considering how many applications embed it.
https://www.tiobe.com/tiobe-index/programming-languages-defi...
The reason those rankings are (mostly) useless is that it's based on search engine hits. An active, effective community that for whatever reason doesn't generate a million and one blog entries a month will not perform as well on the index. This makes it very useful for indicating fads in programming, but not reality.
There's also http://redmonk.com/sogrady/2017/03/17/language-rankings-1-17... which uses # pull requests on github with # of tags on Stack Overflow. Another biased methodology for sure, but it paints a different picture.
This sentence doesn't make any sense.
"Mainstream" means used alot - widespread acceptance.
Lisp is #33 on Tiobe after Cobol, Foxpro, Fortran and Ada. How you can compare that to the takeup of the latest JS nframeworks I don't really understand.
https://www.tiobe.com/tiobe-index/
21 SAS 1.372%
22 Dart 1.306%
23 D 1.103%
24 Transact-SQL 1.075%
25 ABAP 1.065%
26 COBOL 1.055%
27 (Visual) FoxPro 0.932%
28 Scala 0.923%
29 Fortran 0.879%
30 Ada 0.787%
31 Crystal 0.756%
32 Erlang 0.733%
33 Lisp 0.690%
34 Awk 0.662%
35 Lua 0.648%