You can disagree all you want. I work with 18650 LiIon rechargeable packs every day that have three cells in parallel, four of those in series. They are assembled at the factory. I've also taken apart a few high capacity laptop power packs that put 2 and 3 cells in parallel.
Say two non-rechargeable alkaline cells are connected with slightly different capacity/voltage: one cell pushes current into the other. A bad thing, which shortens the life of the cell having current forced into it, and using up charge from the higher voltage cell. Since the one cell is damaged, it shortens its life, shortening the life of both cells. So you don't get double the capacity.
Two rechargeable LiIon cells in parallel, one has slightly less charge and therefore voltage. The more charged cell merely recharges the one with less charge, thereby balancing the cells. Neither has its life shortened. Since the voltage of a LiIon cell correlates pretty well with state of charge, charge balancing naturally occurs when recharging and discharging.
Please don't give me ridiculous examples of paralleling a dead and a fully charged cell, or a new cell with an old worn out cell. I think everyone here knows you never mix batteries in different states of charge and/or lifecycle, even in series.