Dogfooding their process is going to give them adverse results here: Microsoft is paying them to take all the time they want, but good candidates won't be so willing to spend so much time. Already, they're up to a full day of interviews, which is ridiculous. One of the worst parts of current FAANG interviewing is how long it takes to get to the day of interviews, needing to take off from work to attend the interview day, and then getting rejected nonetheless. Not only does this process ask for too much commitment on the part of candidates, it selects for candidates for whom such a commitment is less relatively costly - i.e. people who are currently unemployed, students, etc, and while there are many such people with great talent and potential, respectively, they're also less likely to be strong candidates than people who are currently employed.
One of the key issues in recruiting is how to make hiring decisions quickly. Good candidates don't have the patience for your internal politics to resolve over a month or two to figure out whether they're getting an offer or not; they're just going to interview with other places in the meantime who will beat you to the punch.
Take a resume off the pile. Email or text to schedule a call. During the call, talk about relevant experience / past projects, what each side is looking for, etc. Make a decision during the call whether you want to invite the person for a two-hour interview, and schedule it during the call, first offering an evening time slot for the interview. In the first hour, talk about culture, problem-solving and teamwork approaches, engineering attitudes. In the second hour, pull out an actual current problem and solve it collaboratively. If all goes well, send an offer, and offer to set up a dinner to talk about / negotiate the offer.
It should not take more than a few hours to make a decision on someone; it should not require a candidate to take paid time off. Your hiring pipeline's average lead time should be measured in days.