'Buy' often is not available at the granular cost:benefit price-point that your specific application needs, especially in the startup and scale-up phase. For t

'Buy' often is not available at the granular cost:benefit price-point that your specific application needs, especially in the startup and scale-up phase. For the service provider there is a fairly fixed to linear base overhead so it does not make sense to make an special offering for the 1/10th or less of functionality you might require at 1:10th of the price. It doesn't make economic sense. So for the small business it can mean they get away with a homegrown minimal service at a fraction of the cost, even though the 'quality' of the produced for general applications might also just be a fraction of integrating the 'off the shelf' offering. I've seen some startups running in major deficits simply because they went all out on integrating external services the aggregated cost far outstripped the margin their market allowed for.