Ohhh this is certainly a good topic.
Being somebody who really hasn't played a lot of Smash prior to Ultimate, I found items immediately to be extremely off-putting, toxic, disruptive, and just plain awful to play with when I was new to the game. I felt the same way about stage hazards, smash meters, smash balls, etc. This was because the only place I really encountered them was online, where it was basically complete and utter chaos with everything turned way up and all items enabled on ridiculous stages with smash meters going, which I found to be very unfun.
Fortunately, as I've played a bit more Smash and friends I play with have gotten more open to being casual about some of these topics, we've had a chance to experiment a bit with playing Smash in ways beyond just 1v1 3 stock no items no smash meter tourney stages only.
I think, at least with Ultimate, it absolutely is an issue with overdoing items. Not just items, but hazards and final smashes as well. There are many items and hazards that are way too powerful, overwhelming, and disruptive such that playing with 'items on' without any further specification is pretty unfun, at least to me.
I had a thread open a while back asking the community about creating a, just for fun, semi-competitive ruleset that involved item use. The items were set to low and restricted to ones that required skillful or elegant use, and which were avoidable by your opponent. Good examples of these are the home run bat, green shell, banana, and several others. They're not super disruptive, your opponent can avoid what you're doing, and you have to make a real play to make use of them rather than press a button, receive a giant boost, buff, or minion, and forget.
We actually find playing this way incredibly fun and to be a nice change of pace from strict, competitive sets, as long as we avoid a certain subset of the items.
The same can be said with stage hazards. Some maps have wonderful hazards. They're mild, intermittent, avoidable, and can add a dose of freshness to an otherwise regular match. Then you have stages like the PACMAN stage, the Game and Watch stage, Kalos, the Ness map with that bird thing, and that one with the Pokemon that reverses your controls, that, in my opinion, make the game a miserable experience. It's hard to play with hazards enabled when it puts you into a roulette of having some stages with very disruptive hazards, which, unfortunately, means I'm never going to queue quickplay with hazards or regular maps on.
The same can also be said, from my opinion, about smash meters and smash balls. Some characters have fun final smashes that require aiming, skill, and timing to use, and also give your opponent a chance to avoid them. Other characters basically instakill you with zero counterplay opportunities on your end. Overall, when some characters possess the ability to just make you die automatically whenever they have a full meter or get the smash ball, it makes the mechanic overall feel unfun and unfair, and I ultimately want it off for this reason.
I suppose, it could be summarized like this, at least from my opinion:
I like items, but .... some are so strong and disruptive, I'd rather play with them all off than them all on.
I like stage hazards, but ... some are so strong and disruptive, I'd rather play with them all off than all on.
I like smash meters and smash balls, but ... some characters have final smashes that are unavoidable and way too powerful.
So I queue quickplay with tourney rulesets and only play with subsets of the above with friends in real-life when we want a change of pace from the regular things.