Yes, we've all read the blog about how closing apps doesn't help with battery life [1][2][3].
This is not the only reason to close apps! so get off your high horse about it.
Reasons to close apps:
- You want to keep only a few apps readily available for switching
- You want to keep privacy so the screenshot of an app is not shown in the switcher
- You have apps that behave badly and don't close out background network connections, etc...
- You need to refresh data from the network but the app doesn't have "pull down to refresh"
- You have an app that is badly written and has frozen up
With saving battery life, I have no doubt that technically reloading the data from flash takes more time and energy, but you'd be hard-pressed to demonstrate this in a real-world scenario, and certainly not enough to keep beating the drum about it. Battery life will be affected by many other factors before this one.
If you see people spreading the false information that closing apps saves battery life, go ahead and dispel the notion, but please stop jumping on people at the mere mention of closing apps with no other context.
[1] http://www.speirs.org/blog/2012/1/2/misconceptions-about-ios-multitasking.html
[2] https://daringfireball.net/2012/01/ios_multitasking
[3] https://daringfireball.net/2017/07/you_should_not_force_quit_apps