That's actually great advice for anyone aspiring to learn product design. I couldn't agree more; the best way to learn is by doing and copying, after all, imitation is often a first step toward creativity.
It’s similar to me starting a career in stand-up comedy by copying jokes of known comedians like George Carlin or Chris Rock once you replicate something from scratch several times improvisation boosts possibilities of doing better with persistence related humor learning rate enhancing your advancement thoughts selection process. Also, trying/copying app designs can get you kickstarted sense on how good apps are made efficiently capturing user experience trend statistics including colors theme behavioral patterns etc.
Don't overthink it if you're just starting out as novices; many successful designers started from narrowing big questions down one sided so concentrate on simple platforms. Take small steps until nimble enough while increasing plausible creativity output incrementally derived constructively furthering exploration based deduction either empiral regularity in the filed or main competitor analysis trends.