I enjoy OSRS as a game RuneScape gold in which players can be successful and competitive
I think that what you said kind of depends on what you consider "dedication". In a skill like Runecraft, "dedication" could be equated to spending time, and ignoring the urge to do something more enjoyable/profitable/account progressing/etc. It could be compared to having a lot of cookies within Cookie Clicker (minus offline cookie generation obviously) The most significant measurement of success is more time in the app and not spending that time for other apps. And for some people, this kind of return on an amount is greater because it is more time spent that is.
For me (non-maxed, no skill over 100 days of playtime in the form of Rs3) 99's don't actually have the feeling of satisfaction that was associated with them. It wasn't because it "only" took me 100 hours instead of 400 hours, it's because the achievement at the conclusion of the day was that I'd put in the time doing a dozen or two clicks every minute, without much of thought. Firemaking and Fletching are two that come to my mind. This lack of accomplishment could not be the same even if I'd spent 4x longer on the skills, but that could be due to the way my brain functions, and not applicable to the wider player base.
Some 99 come with an overwhelming feeling of accomplishment, such as Slayer and Hunter. These were skills that brought plenty of variety for me, offered a variety of different ways to train these skills, and gave back to me/my account in the form of drops and unlocks, and also required quite a bit of participation almost all of the time. They were skills I felt I could improve at as I played more often, such as attempting to take on more difficult bosses as part of an Reaper Task (daily boss killing request from Death) or improving my skills at Big Game Hunter (hunter minigame that involves running around avoiding dinosaurs as you attempt to catch the creatures). Receiving the 99 felt like a gold star along the already exciting journey. it wasn't necessarily the end goal, it was just an honor to be awarded along with the skill.
To sum up However, I've never had higher feelings of fulfillment than the feeling of having improved in particular aspects of gameplay. My first victory at Arraxi first kill at Nex, doing my first triple dinosaurs in BGH, running a perfect round of Shifting Tombs and so on and I felt overwhelmed when I achieved these things, and I'm sure that no 99/120 ever will come close for me to feeling the same. And I think that probably is the way it is, with 99's being more a result of something that happens during the road, and not a destination to begrudgingly inch toward.
As a number of people on this thread have said the idea of giving 99's an inherent advantage within the skill capes can be seen as an error in direction, where people are now forced to play through outdated or boring content to gain benefits in the parts of the game that they really want to play. Same with certain high levels of skills being tied to diary and quest requirements. This is great for creating additional goals and benefits to strive for, but a bad idea in the event that the entire journey can be a nightmare that takes away your time from the content that you'd like to play. The "if you don't love it don't do it" method is the one that is used to justify the atrocity of daily scape which has become a part of all aspects of the Rs3, and I imagine we can both agree we do not want something like that coming into Old School, especially not with the excuse of "no one will force you to do it".
There's an elation of achievement with boosts in XP rates and other shortcuts but the success doesn't (and I'd say it shouldn't) originate from the numbers and the time spent. Both games still have plenty of grind fests, no doubt, and I'm convinced they should remain as such. But I do hope that they both focus on more fun grinds, content that's fun for its own sake and not just as a way to get faster/more efficient results to get there.
Give players options that may be lower in XP however, they'll want to accomplish. I do not want Runescape to disappear from the game's grind as there is a market for this game and I think it's a great way to stand apart from the rest Buy RuneScape gold, but I also don't wish to have the patience or time to click three spots repeatedly again to be the main grind for a fair amount of skills in-game. I like that OSRS is a game for people who have a "more experience = better success" mindset can enjoy and be competitive, however I'm not sure that this is the best choice for players.