In very small organizations, perhaps, but the knowledge and skills are not the same, so as soon as an organization gets big enough to have different roles for the code that runs on the server vs. the code that spins up the server, and etc., they tend to do it.<p>To be honest, I've seen more cases where organizations try to combine front-end and back-end, than back-end and devops.
DevOps is more a philosophy than a specific role.<p>Nowadays, there are a lot of positions that are devops engineers, but that's mostly sysadmin-like work but automating a lot by configuring systems through yaml instead of directly working on said machines.<p>Of course, there are also people who develop internal tooling, and platforms enabling the developers to simply create test environment themselves. The real problem here is that every company has their own version of what they think that is ;)<p>Backend developers might work on this a little bit, depending on the company but usually providing the infrastructure is usually not they main responsibility.
In larger organizations it's separate. Developers create software, add features, work with product teams. Operations teams takes the software, installs and runs it. Operations got more and more tasks and started automating more, thus developing their own tools, 'devops' title was created.<p>In smaller companies the backend developer (or multiple) usually also does the devops tasks.