hard to accept that assumption when most proto's are about on par with IS early tech light mechs, and cost about the same in BV. (or more, in many cases)
plus, unlike BA and infantry, protomechs were created to operate independently from the get go in the battletech ground scale. the designs and mini's had that in mind from the start. i mean, the Satyr
Proto's Light Active Probe for example was a cheap way to get scouting ability across the map. running them clustered together in a tight group, you lose the advantage of having 5 of them in battletech ground scale. same for the combat forms too.. yeah you gain some concentration of fire, but it comes at the expense of more complicated rules and more difficult movement. and the ability to split your point up and make the enemy only be able to engage a couple at a time, makes them as survivable as a similar group of light mechs.
in battleforce, the ground scale is different. when even mechs are being run as full lances per counter on the board, 5 proto's as a single counter makes sense too. the ground scale is hugely different.
treating Proto's in Alphastrike as 'mini-mechs' is closer to how they work in regular battletech, and is a lot simpler.
and how much harder would it be to add a "single proto" AS card for each type to the MUL? compared to the thousands of units total?