I haven’t heard that. I have heard that a bigger, custom battery can use used rather than standard batteries, soldering is more reliable, phones are easier to waterproof without a removable back, and (for cynics like me) a soldered battery means the phone must be replaced when the battery wears and loses lifespan.
I once built a HealthKit TV which included a small voltmeter. I think it was the first thing to be built, and it included instructions to solder in the “D” size battery. I did and that battery lasted close to 30 years!
Also, the battery in my pacemakers have lasted 7-11 years. Of course they have no intention of changing the battery, they just change the whole device, which happened last Thursday for me. I’m now 76 and on my 4th device. I hope to make it to #5.