DMARC policy not enabled

I manage an email newsletter for a small, non-profit performing arts organization. Our website is hosted free of charge through a local IT company sponsorship. The newsletter has been running about three months and I have done my best to set up everything so we are clean and compliant (based on great advice found in this sub). So far our open rate is about 52% and click rate about 15% of opens.

I've run our website and sending email address through mxtoolbox.com Everything checks out except it shows our DMARC policy is not enabled. I discussed this with our web hosts and they said you don't want to enable DMARC because it's too restrictive and can cause problems with receiving email. I honestly don't understand the technical end of all this. Our IT hosts have agreed to provide technical support. However it's clear they don't have a lot of experience with email marketing.

Can someone tell me the correct course of action here? If I need to go back and request that the DMARC policy be enabled, what is the justification for this request?

Thanks all for your help!