JWs have become increasingly lax in how they count publishers, counting 15 minutes, and elders filling reports on behalf of publishers. In one case the WT even admitted that a branch exaggerated the number of publishers to impress HQ!
The only extensive independent data we have on JWs comes from national censuses. For example in Canada there were 155,000 JWs in 2001 compared with 138,000 in 2011. Is that growth or decline? In Australia the census showed 83,400 JWs in 1996 compared with 82,500 in 2016. Is that growth or decline Morph?
In fact are there any census results, or other independent surveys that show JWs increasing? I would be interested to know.
Congregation numbers are an excellent way to measure the vitality of any religious community for the many reasons I have given before. That is why the decline in JW congregations is so significant.