Personally I have found it to be quite accurate. The smaller the company you work for the likelihood of 'flexibility' in your role increases. Those companies just don't have the headcount to have a full suite of engineers so rely on people dipping their toes in other tasks to keep the machine ticking along (e.g. frontend devs handling deployment).

With a larger company you will typically find they have already hired specialists to handle very specific tasks. You can always do some things but more often than not the rigor of corporate structure says "If you need anything done in dev ops, please speak to _Bob_ and he will sort it out".

Jumping from the challenge of constantly adapting to different tasks to being there to only do a single 'role' can be quite jarring.