Perhaps a community standard should be established around accessibility? That would seem like a Good Thing for an avowedly open source company to do. Hangouts work (for some value of work!) on everything...
Unfortunately, easy multi-platform video conferencing for 25 people is still a unicorn. Hangouts only work for 10 participants, 15 if you jump through some complex hoops with Google Apps For Work. Yes, you can do Hangouts On Air, which we still use in some cases, but we're looking for a larger number of potential participants in this case since we've usually got 10 people just from Chef in our internal post-mortems. So I fully admit, it's a compromise based on our experience with different tools and meetings.