I have seen too many scenarios where Companies attempt to 'avoid vendor lock-in', or 'select best-in-class', and end up with an unmanageable heap of technologies, that do not integrate well, and which complicates pretty much everything the Engineering teams are subsequently asked to do by the Business.
In my personal experience, it's rare that companies Engineering teams are in a position to change vendors of core systems - due to the complexity of data migration, identity, security etc - and the simple fact that not many Businesses as a whole are inherently 'agile' enough to see real benefits from doing so.
So I will make a bold statement - 'the issue of vendor lock-in is overblown'. Thoughts?