Apple is the new Microsoft.
> having control over the whole product gives you advantages others won't have
And that is exactly what you abandon, as a user of locked-in software.
I concur infsofar, as there is a set of real world applications, where the advantage you describe really counts. Industrial control systems or hardware for medical applications for example.
Note: I own no Apple products except for an original iPad given to me on my birthday. I built my own systems from scratch, as a former electronic engineer, and create web sites on FreeBSD.