Why do some experts suggest that the TIOBE index related to the popularity of programming languages is not reliable?

Question

There are some similar indexes too. Most of these seem to consider several factors like the number of programmers using it, the amount of search engine and github activity, the number of job postings requiring the language etc. So, what is really wrong with these indexes when judging popularity of programming languages?

Answer 1

David Carroll ?

Answer 2

Good answers Martin Taylor !

Answer 3

What is TIOBE?

Answer 4

Seb TheS
https://www.tiobe.com/tiobe-index/

Answer 5

Because it's halfway through the month and they've yet to update their index. I think they delegate this "data driven" report to some intern who only does it when they can be bothered collating the report.
It is not reliable. The most reliable data on popularity of programming languages are from RedMonk.