Why MTA-STS is so rarely used with local e-mail servers ?

[borissh1983 at gmail.com]

Hi,

In the last few days I was trying to figure how many ("home run" , "small 
businesses" or academic ) domains had setup MTA-STS .

Out of 20 domains on this and other mailing lists; only two had MTA-STS. I 
have seen that gmail, outlook and gmx have it, but they 
are not small nor home run. 

As for domains that use  providers with MTA-STS,  I may be wrong, but It does 
not seem 
that the domains 
that use such providers had setup delegation. ( https://tools.ietf.org/html/
rfc8461#section-8.2 ) .

Why is it so rarely used ? 

Why customers of providers that provide MTA-STS do not setup it for their own
domain ?

Test for domain.seclvl.cctld  done by : 

1.Check if there for txt record for _mta-sts.domain.seclvl.cctld
dig +short -t txt _mta-sts.domain.seclvl.cctld

positive result : 
"v=STSv1; id=20190101T020202;"

negative result: 
no result.

2. fetching .well-known/mta-sts.txt 
Good result : 

version: STSv1
mode: testing
mx: smtp.domain.seclvl.cctld
max_age: 86400

bad result: 
HTTP 404, 403 etc ..

p.s. the RFC itself https://tools.ietf.org/html/rfc8461