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.
When a person is skilled in investing and knows the investment strategies, I think it is enough to advise such a person to hold the investment for a long time and be consistent in investing. Although they know these things, sometimes even an experienced person can lose control or get greedy for profits. The DCA method is beneficial for both newbies and experienced people, but there is no reason to look negatively at other strategies if they follow the rules of investment. You need knowledge for different strategies, DCA may be the best for you as a newbie.
The DCA investment strategy is not only adopted by newbies rather it is a method of investment that reduce risk of investing on the investor most especially when the investor don't have so much capital to adopt other investments options hence, both experience investor without capital still adopt the DCA strategie.