Yes, but the Snapdragon and Celeron have drastically different architectures. A big part of what makes the M-series of chips special in terms of performance-per-watt is that they are very opinionated - snapdragon 8c is a 'compute platform', the M3 is a chip designed up-front targeting a set of devices with a specific set of capabilities.
Having seen many other chips with such a design methodology (3dfx Voodoo 2 springs to mind), I'm not comfortable saying they could just wedge an additional display output into their current architecture without ramifications.
So no, I don't think it is a marketing/moneymaking thing. I think it is part of the design trade-offs of the chip.
To put it a different way - if they had to choose between the chip having 2% faster GPU performance, one more efficiency core or an additional display output, they'd have been nuts to pick the display.