Its already discussed multiple times.
SE vs TE jet, Heavy Class vs MWF,active stealth vs passive stealth, Turbojet vs Rurboprop, Air breathing vs dual pulse etc etc.
what’s important is how you achieve the desired goal and not what is used to do so.
PS: never saw (in current times) modern forces like USAF/USN or RAF, French Forces using such stupid classification for procurements
USAF is entirely centered around such a classification, they have been following a two class system for decades. So has the USN, as has the SU and Russia, and China, and of course India.
A class system is used when your army, air force or navy is massive and cannot just operate on a single criteria. Those who dismiss the class system are typically Europeans since they do not have equivalents in a higher class like the Americans or Russians. For example, the Europeans lack a heavy transport, they built something that sits in between the C-130 and C-17 called the A400M Atlas. This is suitable for the Europeans with their small militaries, but it's not suitable for large forces, especially those that also want to transport their battle tanks. So, for India, the Atlas is too light for the strategic role while being too heavy and expensive for tactical roles. Hence we use a three class system, light (C-295), medium (C-130J/An-32 replacement) and strategic (C-17, IL-76).
As for the helicopters, due to our large force size, an unproven indigenous design and varied geography, we have settled on two light helicopters of two different classes. The indigenous one is a true light helicopter with adequate payload for its mission, while the imported one is basically a proven mini-Dhruv, with two engines for increased survivability in battlefields and bad weather conditions and with higher payload. So this creates two different classes for us. And there will naturally be a price difference between the two.
Without a class system, large forces wouldn't be viable. Or the IA and IAF would choose 400+ Ka-226T instead of splitting the buy between a light helicopter and a light-medium hybrid.
The Europeans are largely a one-class force because they don't want to or can't afford anything more than that. Which is why they design just one type of fighter jet or helicopter or transport at a time and replace their old ones with it.