Checking charts can be useful, but understanding what caused significant market shifts in the past and calculating how much influence such events have now and in the coming years is also very important.
This is the very statement that everyone should know as I definitely agree with you.
Sure, the price history of index showed a significant increase to its price ever since it started way back in 2009. But understanding those key events that lead to its price right now should be taken into account before you invest. While a person may use its price history index as basis for investing, you must also know the reason on why bear and bull runs happened within those years also.
A person should not just blindly invest without knowing on why the price of BTC increased in the first place. Not to mention, even during those bullish runs, there were some bearish runs that caused the price of BTC to crash in those said years.