It's rarely known McAfee used Avast engine in past in own AV (before buying Sophos)....
Also , just look at other companies ... they have these "web" scanners ... (e.g. Kaspersky, McAfee, PandaSoftware etc) ... they in fact are "like" free AV edition...
the whole point is ... most of Home users can't affort to pay "expensive" licences for "just AV" ...
either the price must be low or none ... 90% of world population is not in "rich" status ...
free products are also excelent testbed for companies ... they can "see" what people demand and then re-implement this for profi users and company usage ... experience is what matter !
Czech companies are widely known for this approach and see
it works