I agree with your assessment of a commodity business, but this is in the long run. If we look at the current packaging market in India, apart from the 3 large packaging companies (one of which is TCPL, which imho has one of the most aggressive management I have seen in listed Indian companies), most of the market share is with unorganised players. This is a very unglamorous in which you need 1) large scale (which TCPL has in abundance) and 2) major focus on costs to succeed.
TCPL’s scale and focus on value added packaging (the rotogravure and UV printing and other value added stuff) requires very heavy capex out of the league of smaller competitors, while TCPL’s high stock price as a listed company allows it to raise large equity capital at 3x BV as well as lever that up with debt, giving it large access to funds. Yes, this is not something that will happen for 100 years, but if TCPL grows at 25% for that long, it’d be larger than india’s economy 
(point being that 25% growth for even 5-10 years is huge and has insane upside…)