Years ago, if you purchased Eye of Skadi for Anti-Mage or Satanic for Medusa, you immediately received four reports and mutes. In Dota Allstars some items and abilities had a special status - a unique attack modifier called Orb Effect. This is an extra attack bonus: armor reduction, additional damage, or a special effect that migrated to Dota Reborn. Two Orbs or more Orb Effects didn't work at the same time. So, imagine that you stashed Satanic and Desolator together.
In this case, Desolator will not reduce armor until you drop Satanic. In addition, when you pick up Satanic again, the item will no longer heal your hero. Due to this game mechanic, the player shouldn’t forget item build specifications. Since 2016, Valve abandoned this mechanic and removed all Orb Effects. Therefore, today you can't even envisage that some items do not stack.
Prior to patch 7.23, Dire and Radiant had one courier. Moreover, you should buy it and improve it into a flying form. To tell the truth, personally, I played dozens of matches when the courier appears at the tenth or fifteenth minute or even no courier at all. Nobody wanted to spend 200 gold to purchase a courier and everyone waited for somebody else to buy it. In the majority of cases, no one bought - otherwise you are a “weak worm”.
It seems crazy to present-day players, but who said that Dota 2 it’s an easy game! It was very critical to lose the courier, because his loss means that your team would not receive items. Therefore, the gameplay of many pos-4 heroes was based on sniping “donkeys”. Bounty Hunter, Nature's Prophet, Riki, and Monkey King have always been in the mainstream.
Let's move on to items that Dota community will no longer observe. Some of them you can pick up as neutral artifacts up to this time. I hope you still remember Poor Man's Shield that won't kick you out of the lane, as well as Iron Talon that was the best item for jungling Legion Commander and Bloodseeker. For a while, Talon removed half of the creep's HP and even worked on Ancient Creeps! Think back to the Ring of Tarrasque.
It seems to me that Phantom Lancer and Spectra still miss this Ring over and above Diffusal Blade 2 recipe. Also, Necronomicon summons gave True sight, removed wards, purged mana, dispelled, and even dealt volcanic damage. Sometimes they did more than my two sups. This is probably why Valve removed them. Well, there are fewer Lycanthrope and Beastmaster spammers in ranked.
Right now Skull Basher is an ordinary item in Dota 2. The ongoing Dota version allows you to purchase Basher for Void or Slardar, because it works. However, imagine being stunned by both birth bash effect and Skull Basher 1 sec stun. Previously, Basher didn’t apply the double bash effect, if you play these heroes. Icefrog removed this nuance in patch 7.07. Contemporaneous bash set stun for just a couple of seconds. Sometimes I think that it’s too lazy for Gaben to rework the mechanics of one hero, so he just banned the item.