Microsoft Designer as a no-download browser-based design tool is the accessibility argument that explains its actual user base
The path from login to finished design being the tutorial content rather than the feature explanation is the honest representation of what Designer is built for: people who need a finished visual output quickly without a design background or design software.
The standard design workflow, log in, choose a template category or start from a text description, customise, download, is accessible enough that people who would never have opened Photoshop or Canva will use Designer because the friction is effectively zero for someone already using Microsoft products.
The tool not requiring software installation being specifically mentioned as an advantage in the tutorial tells you something about the target user: someone working in a managed IT environment where installing new software is either difficult or not allowed.
The AI generation doing the heavy lifting of making the output look professional without design decisions being required from the user is what makes the tool viable for its target audience rather than just accessible to them.
For IT managers and department heads: how many teams in your organisation are currently using unsanctioned design tools because the approved tools are too complex and would Microsoft Designer's accessibility change that?