4 12V 200AH deep cycle lead acid batteries cost $1552 on Amazon and hold as much energy in practice as a 100AH 48V LFP battery which last 15 years, minimum, and only costs about 6% more up front. (Not linking to specific batteries in order to not shill for them, but do a little searching for 100AH 48V 4U server rack LFP batteries on youtube, and you will find dozens of tutorials.) Quality inverters last 30 years, not 10.
Are these people TRYING to light money on fire? Are they fronting for someone by trying to make solar look impractical? Or are they just stupid?
"For example, if I omitted the battery storage of my solar installation, my system would become about 10 times cheaper: ..."
and then goes further along this interesting line of reasoning...
To be clear: batteries are still not cost effective relative to a grid connection, but everyone who has an off grid system goes for LiPO for a reason.