There's a pretty direct tradeoff between BOM cost of an ARM microcontroller and ROM/RAM. ESP is a little different with external spi flash, but the tradeoff is

There's a pretty direct tradeoff between BOM cost of an ARM microcontroller and ROM/RAM. ESP is a little different with external spi flash, but the tradeoff is mostly there still. So there's a lot of pressure in product development to keep technical costing down by using C/Assembly and choose technologies like UDP vs TCP or CBOR/Binary protocols vs JSON.