For good movies it probably doesn't make much of a difference. But most movies are not good. There's a huge gambling element to seeing a movie, and a leak gives away the outcome.
You can check some stuff they pred here: https://www.srrdb.com/browse/SPARKS/order:date-asc/1
As you can see (sorted by oldest because surprisingly many things have sparks in their name), it's mainly retail rips.
In fact, few scene releases before COVID would actually impact theatrical openings, since the movies only get released weeks/months later on phyiscal media/streaming. The only thing you get before are crappy camrips/telesyncs.
They do however usually manage to acquire the media a few weeks before the street date, which is why streaming releases are now a few weeks before the physical media releases.
Adding DRM has a cost and I'd rather not do it but it's quite clear to me that not having it would impact revenue.
The US is sheltering a diplomat(spy?) who negligently ran over and killed a British civilian as we speak, but these guys are the real danger.