ICS file automatically in outlook.com not desktop?

Hello, apologies in advance for the stupid question but this is my scenario.

I use 365 outlook.com only and often sign up to events etc with external partners, the option to download the meeting is automated afterwards but as soon as I click on the downloaded file it opens Outlook on my computer (every time) which then takes ages to update all emails etc. finally I get to save the invite to the calendar then I close it and a few seconds later it's in my outlook.com calendar. 

My question is can I automate when clicking on a ics file to get it to open/save in outlook.com instead? 

Can't MS make this an automatic feature if you are using online Outlook?

Many thanks for any responses...