I am not a hosting system operator, but I have been managing our SmarterMail environment for more than a decade, and watching Microsoft since Windows 1. I will offer some observations, but others will have to judge which ones are safe to use as a selling strategy.
Microsoft dominates by bundling and bundle pricing. An early attempt was bundling Internet Explorer into Windows 95, in an attempt to wipe out the market for other browsers. They lost that battle, but they have one most every battle since. They wiped out WordPerfect and Lotus 1-2-3 by bundling Word and Excel. They dominated on-premise email by superseding standards-based IMAP with proprietary MAPI, EWS, and EAS. The user interface was superior to once-dominant IBM PROFS and provided synchronization features that could not be obtained on Unix/Linux system. So they get credit for anticipating a market need and addressing it, but the consequence of that success is that customers become dependent on that vendor.
Microsoft is continuing that process with the other products that have been discussed here. Teams integration and bundle pricing has effectively pulled customers away from remote support solutions that have been around much longer. Notably, Teams must be installed on a local PC for the support person to obtain remote control. Once installed Teams launches every time a user logs in to that device.
Microsoft also dominates by applying coercion to existing customers. Nobody wanted WindowsME, Windows Vista, or Windows8 based on features, but Microsoft decided that these would be what everybody must buy. When that process failed to force upgrades at the speed that they wanted, Microsoft use end-of-support to solve their problem. When Microsoft decided that they wanted to own cloud computing, they used pricing to force customers away from on-premise Exchange and onto Office365. It was only possible because customer had already become dependent on the Exchange.
We have also seen the coercion applied with Outlook. The first coercion was exposed when Outlook forced us to use Autodiscover to configure their protocols. Then they used Autodiscover to silently connect to their servers. For everyone that does not use Office365, this is a malicious act which sends confidential information to Microsoft without permission. But the point is (probably) not to steal your credentials, it is to eavesdrop on your data, presumably to feed their A.I. Model The current extension of this coercion is “New” Outlook. It is installed automatically by Windows Update, and displaces old Outlook by default. If used, it forces traffic through Microsoft servers without permission and without notification.
Then there is the quality of the Office365 environment. One evidence is the way that Office365 uses ARC data to report security issues in email messages. A credentialled login is reported with a Received record claiming a MAPI connection from a server to itself, and an initial ARC set that asserts SPF PASS, DKIM PASS, and DMARC PASS even when those assertions are actually false. More importantly, Office365 accepts uncredentialled SMTP connections. It uses an ARC set to report actual results for SPF, DKIM, and DMARC, but thereafter proceeds as if the connection has been validated. It will happily apply a DKIM signature to an unauthenticated message, so that the recipient is duped into believing that the message originated without impersonation.
The quality of the environment is also indicated by the obvious spam that arrives to my system, even though it carries message headers indicating that the message was carefully checked by their spam filter yet allowed to proceed.
More subtly, it shows up in DNS timeouts, which are exposed by DMARC reports. I have been told on an IETF forum that Microsoft had a known problem with DNS timeouts, but more than a year later, it does not appear to be fixed..