I think one of the most interesting things to ask photographers is their opinion on buying presets/using someone's presets other than their own. I'm not here to condemn or praise anyone, these are just a few of the pros and cons I've found during my own research of using presets.
Sunset photo without any preset.
If you're a photographer in the sense that it's your full time job and not just your hobby, presets are a fantastic way to maximize your workflow and get photos edited extremely efficiently. Especially if the preset was created for a photo taken in the same kind of environment as the shoot you're editing was, then it can save a significant amount of your time spent in Lightroom.
Presets can be used as a tool to help learn how to edit photos in a certain aesthetic. Personally, the main reason I've bought presets (guilty as charged) is to, paradoxically, actually learn how to edit. I'll often duplicate a photo, apply a preset to one of the images, and then work on the duplicate image until I'm happy with how the image looks, I know I'm finished when I'm more happy with my own image than the image with the preset.
Something that is so attractive about presets is that they are very effective at editing photos in a cohesive fashion. So that if you're going for one singular feel throughout your galleries, using one preset can give you that cohesive look. Just make sure your color temperature and exposure is even throughout your individual galleries.
Mid-day photo with a preset.
My biggest problem with presets is that I have a hard time being proud of the images I use presets on...which is a 'me' issue. But from my perspective I spend a lot of time arranging a photo during the shoot and it almost feels dishonest to myself to rely on presets to do the editing. And this is where I have personally been able to justify buying presets. They've helped me grow as an editor. I've chosen not to rely on presets to edit my photos. Presets have been a huge guide for me and have taught me how to turn green shadows into golden warmth, how to make skin tones pop, and can give me a direction to point toward when I edit.
Presets are not one-click miracle workers. There is typically still some editing that needs to take place before a photo is finished. It can be huge edits, or it can be just adjusting the exposure and color temperature. But either way, even if you buy presets, you will need knowledge of how to edit in Lightroom.
Whichever way you lean in terms of buying presets, there are valid reasons for both. And maybe that depends on an individual's pride of being a creative verses the pride of being a business owner....or maybe it has nothing to do with either of those things.
If you use presets, that doesn't make you a cheater, it makes you efficient. If you don't use presets, that doesn't make you high and mighty, it makes you the full influencer and developer of your image. At the end of the day, what matters is what's important to you and your photography as well as delivering quality photos to clients, and the path getting there is going to look a little different for every photographer.