Well, I think fundamentally OTAs are a commoditised service right so my expectations of them aren't high and they aren't something I use for a luxury stay or special occasion. Presumably you mean OTA in the sense we usually talk about it, e.g. there's no human interaction in the process.

I don't think there's much friction in that anymore; the pricing is transparent, the bookings go through immediately and are recognised when I arrived. I mostly use OTAs for transactional stays, most often in countries where booking direct is annoying or where I might not want to store my payment details with the hotel. I use Booking for those and haven't had a problem in 10+ years, plus the flexibility and Genius discounts are appreciated. The only real pain point I've experienced is when I need to make a change, like leaving early, but it's always been fixed - it's just friction having to call them, waiting for them to call the hotel, etc.

For anything else I will book direct with the hotel. For special occasions or more tricky locations I'll be booking direct or using a travel agent, not an OTA. For those stays either I know what I want to a certain degree and will facilitate that myself, or if I'm using an agent it's because I value their relationship with the property or need them to be hands-on with something along the way (like activities or transfers or something extra I need during the stay).

When you say it makes a real difference, what exactly are you proposing? It's hard to provide much useful commentary otherwise.