The point of reaper being a greater challenge for experience players is correct - that is the intention of reaper mode. However there are a few things I would point out:
1) Having benefits that make that mode easier is not necessarily making it less of a challenge. In terms of R1 content, it does help to have more reaper points, and makes your character more survivable. However, R1 in itself is not a particular challenge (except for newer players, who would likely find R1 a challenge even with many reaper points because they likely lack things like quest/game knowledge, gear, etc). In terms of high reaper content, again having more reaper points can help you survive one or two more hits, but if you've run high reaper before (especially high reaper raids), you'll know that you can have 156+ reaper points and all of the past lives, and still get blown to bits due to improper scaling, rng, invisible circles, etc etc.
2) If the argument is that there shouldn't be benefits for players who are trying to play more challenging content, then would you argue that past lives shouldn't be a thing? Champions were added to Elite mode to "add a challenge", but having a bunch of past lives makes it even easier to deal with them.