Outlook on the web vs Outlook desktop app
You may have concerns about using Outlook on the web. However, Outlook on the web is in most cases a better choice than the Outlook desktop app. The main concerns over using the desktop app can be overcome relatively easily. In some case it may still be more convenient to use the desktop app though.
Always easily accessible
One significant advantage of using Outlook on the web is that it can be easily accessed with a few simple steps without any need to install anything which is convenient when using a different device than usual. The Outlook desktop app on the other hand needs to be installed.
Standalone app
You must open Outlook on the web with a browser. It is more convenient to use a separate app that has a distinct icon on the taskbar. Fortunately, it is easy to get Outlook on the web to behave like a native app.
You can make Outlook on the web behave like a native Windows app by selecting settings while on the Outlook page, then choosing More tools -> Create shortcut..., this creates a Progressive Web App (PWA) which behaves quite similarly to a native app. Optionally, you can select Open as window to hide the browser UI elements while using this shortcut to access Outlook on the web.
Support for multiple organizations
You can’t use inboxes from different organizations on the same Outlook window. This can be a problem although in most cases you only need to manage one organization’s email. Keep in mind that you can still have multiple groups or shared inboxes in the same view as Outlook on the web, just not inboxes from different organizations. If you do need to manage email from multiple organizations, then you can create different browser profiles.
To do this, you can go to account options and create a new profile. You can then create multiple shortcuts to Outlook instances with different profiles. This to some extent makes it easier to work with multiple accounts from different organizations.
Offline mode
The Outlook desktop app can function offline. You can read email and write email while offline. When you send an email it will be delivered when you go back online. In most cases it is not important if you can also access Outlook while offline as in practice most offices will be always online. Outlook on the web is currently unable to offer offline access so if you do need offline access, you should use the Outlook desktop app.
Summary
In conclusion, if you don’t need offline mode or support for multiple organizations, you should use Outlook on the web. If you do need offline mode or support for multiple organizations, you need to consider how big of a problem these limitations pose.