It's kind of an ANSI thing. If someone prunes 3-4" diameter wood, which is an ANSI pruning best management practices booklet recommendation, you don't benefit from a big chipper. Likewise, if there is narrow access for a chipper and mini, that bigazz chipper will not help. Lastly, if your market does not favor chippers for removals, (as is the case in my area) you don't want to be saddled by a big chipper while everyone else is cruising by your hunk of heavy metal to the next job. If I go south two hours, the grapple truck fees go up tremendously (3X in summer) and I would want a large chipper there.
"Commercial" is an interesting word. It seems to be an excuse for cowboy tree care rather than a statement that one is working at a business. Being located at a business usually does not bear on what care the tree needs. A parking lot does bear on specifying care, regardless of whether it is at a business. It is better to categorize work with regards to the tree/forest and the ANSI standards.