The shifting of religious practice in the US impacted scouting as well. Mainline Protestantism and Catholic Churches are on the decline - that’s the backbone. In the Catholic environment I grew up in, Boy Scouts kept kids engaged after communion with the parish.
The other issue with the model is that the local organization leadership reflected the old model. (ie. It’s a bunch of white dudes) The most traditional, growing communities who would be attracted to scouting with Catholic and Episcopal communities are Hispanic, Filipino and in my area Indian.
It is sad. I was involved from age 7-14 (when we moved) and loved it. But institutions only survive when they can grow themselves.
My time as a Boy Scout in Maine was life changing. It was not just about activities and skills (although there were many), it’s clear that the leaders of that Troop saw Scouting as a kind of secular education in ethics and community. They made the various Scouting accomplishments (ranks, merit badges) feel like milestones along a path of self improvement. It felt important.
When my family left Maine, the local Troop was weird (the Hitler Youth comment by the earlier poster tracks) and activities consisted of playing checkers in a church basement. In particular, peer bullying of younger/new kids was routine. I lost interest at that point and stopped going.
It’s been difficult to follow news of Scouting’s decline for me, because I have seen how positive it CAN be. But perhaps local Troops like this are rare.