Reaver VS Colossus

However, there are a lot of things that colossi introduced in protoss technology that reavers honestly cannot replicate. Mainly, the colossi is able to directly attack armies regardless of height that a reaver cannot do without exposing it immediate death.
Since Starcraft 2's new introduction with improved elevated terrain gameplay (such as reaper harass, proxy pylon, blink stalker, aerial vision adavantage especially with terran), Colossi play honestly makes it more useful for various types of strategy. While indeed Starcraft 2 isn't the type of game for unique strategies and relies more on timing, the changes and variability of the maps honestly cannot make reavers feasible.
Going back to my statement with height differences, a low ground colossi can attack high ground units, and can attack units in areas where low ground cannot move up or attack without drops nor aerial vision. A reaver simply cannot do that.

Theoretically it would definitely be the same thing. However, a reaver simply cannot have the same versatility as a colossi, simply because it is a lot more well-defended than using a reaver + shuttle combo. In addition, the base issue still lies on the reavers capability in being able to inflict the same amount of DPS as would a colossi. Forgive me if I don't know much to SCBW, but a lot of attacks and retreating now focuses on being mobile and agile, mainly via kiting with range units, or stalling time.

As far as I know, Colossi are able to kite, retreat to high ground, and safely inflict more damage without harm (only if there is no aerial vision). Along with sentries, a colossi can either safely snipe behind blocked attackers and buy more time, or during PvP, a colossi can break a FF and continue the pursuit with the rest of the army and possibly end the game.

With reavers (we will assume that the reavers are not massive still), a lot of time is spent on dropping a reaver and picking up a reaver while attacking. Because SC2 focuses almost entirely on timing, a lot of time is potentially wasted due to such micro. And due to the examples I mentioned with a colossi, a reaver simply cannot perform the same actions as a colossi would. Although the DPS is highly debatable, a reaver attacks about the same speed as a siege tank, and it also requires the scarab to take additional time to travel and explode on the said target. Since shuttle + reaver is how it makes it versatile, would it not be the same for the opponents to do the same with units similar to reavers, such as a medivac picking up exposed units like seige tanks?

And we even haven't factored in other SC2 mechanics as well, such as immortals and potentially scarabs being shot down with PDDs.