I think that question is more "how many different makes of van can your delivery company afford to maintain?"
Which is an analogy for "how many different programming languages for the same task of serving a web api can you company afford to support?"
The majority of programming languages (c# definitely included!) are "general purpose", i.e. they can be used well enough for almost all tasks. They're not so different as a truck vs. a bicycle.
The issue is not so much "we need firmware in Rust and statistical analysis in R" - that's fair! The issue is more, as others have said, web apps or similar in multiple equivalent languages. This is an overhead. If you take on that overhead, recognise that 1) it has definite drawbacks and 2) for mundane tasks, the advantages aren't large. and 3) chances are your organisation is like most orgs - you don't do all of firmware, statistical analysis and web apps, in house.
Car models get maybe refreshed annually, bigger changes a couple of times a decade, if that. Vehicle fleets are often aging out with these timelines.
So if we either stretch the fleet management analogy to 50 years, or software applications only lasted 3-5 years maybe it IS fair to say the both have either a lot (former) or very little (later) inconsistnency?
> Car models get maybe refreshed annually, bigger changes a couple of times a decade, if that.
.NET gets refreshed annually. The last bigger change was nearly a decade ago. So not all that different.
But I don't think that the analogy stretches, really. e.g. where I am all .NET apps are .NET 8 LTS or 9, and will be all be .NET 10 LTS by middle of 2026. You can upgrade an app to a new model year much more easily than a vehicle. The "software application, on a SDK major version" only lasts 1-2 years.
Which is an analogy for "how many different programming languages for the same task of serving a web api can you company afford to support?"
The majority of programming languages (c# definitely included!) are "general purpose", i.e. they can be used well enough for almost all tasks. They're not so different as a truck vs. a bicycle.
The issue is not so much "we need firmware in Rust and statistical analysis in R" - that's fair! The issue is more, as others have said, web apps or similar in multiple equivalent languages. This is an overhead. If you take on that overhead, recognise that 1) it has definite drawbacks and 2) for mundane tasks, the advantages aren't large. and 3) chances are your organisation is like most orgs - you don't do all of firmware, statistical analysis and web apps, in house.