Besides resources, for companies that do not operate at an planetary scale like Google, Facebook et al., I'd argue we have reached a point where a lot of the co

Besides resources, for companies that do not operate at an planetary scale like Google, Facebook et al., I'd argue we have reached a point where a lot of the common problems have been thoroughly solved in multiple ways for a while now and you can pick one. So it is not just to save time & money. Outside the core business and if the evaluation of third party products has been done decently well (which I think is more often the actual problem) there is often basically zero need or benefit to come up with something custom.