Obviously this isn't for all matches but I've seen bookies running it as a promo for big matches. Obviously the goal is to keep some money going around on the platform. It's usually for single bet tickets that this promo can be utilized. Probably they're thinking of people keep depositing the platform is going to make profits from other markets that will have an edge.
If it isn't for every matches, I think it can work as marketing to boost the traffic and betting volume for the platform, at same time the casino ensures its sustainability as business. For gamblers, however, I don't know what to expect.
It would be interesting to watch an experiment where a gambler defined a limited bankroll to place bets solely on zero house edge bets. Then we could analyze how impacting house edge is for long term gamblers and how possible it is to make profit from such bets in volume.