DCA is not the only strategy to invest in Bitcoin. There are different strategies for investing, even different investors adopt different strategies for investing. Those who don't have a lot of money to buy a large amount of Bitcoin at once but have a fixed source of income can opt for the DCA method of investment. This method will be most helpful for them as they will buy bitcoins with fixed amount of money periodically and increase their investment.
It is important to invest and hold Bitcoin. It is not very important to focus on how you are investing. However, for a newbie, you can recommend DCA. For experienced people, I would leave it to them, because they know and can use different investment strategies. DCA is not the only investment strategy, but DCA is the most discussed because it does not confuse newbies and allows them to invest without much knowledge.
You are wrong; it is always important to focus on how you are investing in bitcoin so that you will not invest in bitcoin in such a way that it might stop you from sorting out your daily expenses, which might likely get you off the game partially or permanently. The DCA strategy is not only meant for newbies; even old investors in bitcoin can also adopt the DCA strategy in accumulating since they will not be buying all their bitcoin at once, and if they figure out their discretionary income will allow them to accumulate bitcoin with a lump sum at some point without them finding it difficult to solve their daily expenses, they should go ahead with it because it will help to increase their bitcoin portfolio.