This is an organisational mistake though, a company is supposed to assess and validate these softwares and platform and to propose an information system that holistically enable collaboration while fitting the company’s maintenance capacity and its social and/or business interests.
What you describe here is a SMB workflow that lacks any king of IT service management and enterprise architecture, data protection is not there, there is no or low interoperability between the different business units and when there is, it’s more like a working cooy than a relational system based on company’s core domain (data models and documented methods).
To say it, it is not professional and put people in highly critical positions. Designing an information system while not being so unaccessible to the common , is a skill and you need a specific way of tackling problem while keeping those you create under control.
There should be a corporate reality and an SMB one, while what I describe here as the SMB organisation is widely spread in bigger companies too and some SMB specialize on on the matter or can rely on centralization of decisions around a leader or an expert to work professionaly.
The way it is done in big companies is either a 200k job or a collaborative work involving different layers or teams under the facilitation of system engineers or people alike.
Some try to tackle it using ERP plateforms which is arguable since they face a new employment market (and expensive consultants), vendor locked in, low adaptability and risk of corrupted workflows.
You mention each silos would buy everything they need by their own but it shouldn’t work that way, the internal marketplace, supported by batch packages and partnerships, can help resuce costs, provide a unified validation and can receive and document the needs of the company while promoting needs between silos and ensure a good change management before and after implementing new internal products.
The same way you wouldn’t let anyone pick the money they need in company budget before the big guys discuss it and compromise on where to give the money, you don’t let people cumulate IT assets (be it hardware or software) without the proper layer of compromises and priorisation.
More with that is that you should make sure that with each asset comes liability.
You need a liability framework regarding data protection, intellectual property rights, industry specific requirements and inclusion.
This would actually be the kind of too much to deal with if people adding more and more software to their workflows even gave a fuck about the consequences of what they do on people and the overall sustainability of the company.