Disagree. It depends on how it’s being used. Just like computers before, flagship phones have become powerful enough to last quite a few years and OS upgrades. iPhone 5s is still pretty usable, but if you bought it new when first released, you would be on second or third battery by now. My 1yo 8 is expected to be in service for at least 3 more years
As phones are becoming increasingly expensive, more people keep them longer too
There's also been a marked flattening of the functionality improvement curve in recent years. In terms of the functionality that most people use most often, today's flagship phones aren't all that different from those of three or four years ago. Most of the current crop's improvements, in my opinion, are more gimmickry than anything else; and to me, the gimmicks don't justify the price -- especially when easy battery replacement is an option.
Using the LG V20 as an example, the original price for the AT&T-branded model was $829.00 without subsidies. The AT&T-branded model of LG's current flagship phone, the V40 ThinQ, lists for $949.00. The V40 sports six cores vs four, a 2.8 GHz processor vs a 2.15 GHz processor, 6 GB of RAM vs 4 GB, a slightly larger screen, and slightly better cameras (and more of them). So there are some actual hardware differences that probably justify the higher base price --
if a user is actually going to make use of those improvements.
For more average users who happen to already own a V20, however, it's questionable, at best, whether the differences between the V20 and the V40 justify laying out $949.00 for a new V40 versus spending between $15.00 and $39.00 for replacement batteries for their V20s. Genuine replacement batteries for the V20 cost $39.00 directly from LG, or about $15.00 from unquestionably trustworthy third-party sellers. Are the V40's functionality improvements worth spending $949.00 compared to spending $39.00 for even the most-expensive replacement battery option?
For that matter, does the V40's functionality improvements over the V20 justify buying a new V40 versus an "old"-stock, new-in-box, AT&T-branded V20 for ~$230.00? Does the V40 offer more than 400 percent the capabilities of the V20 for average users?
I suppose for some users, it does. There are people who use their phones for resource-intensive tasks like audio or video editing, or who need cutting-edge cameras because they use their phones for professional photography. Maybe for those folks the enhanced hardware will make a big difference.
But what about for the rest of us who use our phones for talking, texting, occasional navigation, and the odd selfie once in a while? Will we ever sufficiently exploit the possibilities of the improved hardware to justify a $949.00 expenditure versus a $15.00 to $39.00 expenditure for a new battery?
It's all a racket, as far as I'm concerned. With the sole exception of users who need phones that are actually waterproof (as in meeting IEC IP standards x1 though x8, which only a tiny fraction of current phones actually meet), there's really no good reason, from the consumer's perspective, to make a battery non user-replaceable. As I mentioned earlier, I'm not even sure that a truly-waterproof phone with a removable battery couldn't be built using a simple gasket and a tight-fitting battery door.
But for manufacturers who want to sell phones, this new twist on the time-dishonored tactic of planned obsolescence makes perfect sense; and unfortunately, as long as consumers are too passive and stupid to refuse to go along with it, the manufacturers will continue to get away with it.
Rich
Of course he uses it mostly as a phone. 
