ScrumBut - the biggest reason is whole company buy in
A lot of companies and teams say they are doing agile or scrum and it turns out it is scrumbut (Scrum without the core processes that make it work). In my experience the biggest reason for ScrumBut is that the company as a whole hasn’t bought into the cadence that scrum, agile, kanban (whatever you want to call it) requires to function well.
When development teams use Scrum to protect themselves from the rest of the business you might have something better than before, but you are not going to reap the rewards of agile processes. In smaller companies it should be easier to get the whole company to buy into the process. You just introduce it for the development team and then start shipping frequently. If they were not agile before they will very quickly see the benefits and as everyone is so close the company will adjust.
In larger companies this is much harder and the timescales for change might take a long time as there are people that can cause ScrumBut who are not even aware of the difficulties of software development. This is where someone has to hold that vision and has the patience to slowly push the company in the right direction.
A good way is to take a small self contained project and demonstrate the value and then use that as a model for other projects.
The thing is the value of Agile is pervasive and once you start on the journey eventually everyone is one over. Just as long as someone keeps pushing it along.
