Wow, very surprised to hear that those mRNA come from actual living, metabolizing, (albeit single-cell) organisms. Why do they do it that way? When you order

Wow, very surprised to hear that those mRNA come from actual living, metabolizing, (albeit single-cell) organisms. Why do they do it that way? When you order DNA plasmids from places like Addgene the stuff they ship you is chemically synthesized using enzymes rather than and entire complete living cell, right? I would've thought Pfizer would do the same thing and then transcribe that DNA into mRNA. Is it because of the massive quantities of material they need to produce?