Actually, that’s not the question I was asking. I wasn’t asking how much of a time investment it should be.
The question I was asking was whether people thought it should be feasible to complete the journey on standard equipment achieved while levelling to 100, or whether there should be a significant post-100 grind to get post-100 equipment and/or above average skill level required.
Based on your response, I’ll take it to mean that yes, you think that players should be required to grind beyond level 100 in order to get the equipment needed to complete the seasonal journey. 
My point being is the Season Journey requires players be active pass level 100. You are proposing the Season Journey should end at level 100. The fact of the matter is: it isn’t require nor demanded from the player to complete the Season journey. Players are heavily incentivize to partake in the Season Journey. Anyone can ignore the battle pass and still play diablo. People choose not to.
For the regular season journey, I was able to complete it with no upgrades to my gear.
Andarial and Lilith I needed to upgrade. (I honestly found Tormented Duriel incredibly easy).
Andarial, I needed a few upgrades, but that fight wasn’t too bad except for the last 15%. If you can farm Pit 30, he should be doable.
As for Lilith, I needed a ton of upgrades. While it’s more skill based than previous seasons, the fight is still a gear check. I believe I first attempted it at Level 100, where my barb had 29k dps and 19k health, and that didn’t work so well. I finally defeated her when I had about 40k dps and 48k health, along with a Shako. (That required me creating and completing the Iron Wolves multiple times though.)
(For Lilith, with 9200 Armor and max resists, each hit did about 16k damage without the damage multiplier. When I finally defeated her, I had a 5 stack of the damage multiplier. The stacks occur if a wave hits you, you touch the edge of the circle, she lands on you, one of the bolts hits you, etc.)
An average player should be able to complete the seasonal journey, as such it should not demand the completion of the extreme endgame - Lilith, tormented bosses or pit 50+. That being said there is nothing wrong with adding seasonal challenge quests with cosmetic rewards from the shop - defeat x ultra powerful thing by day y and you get z shiny that would otherwise require real cash.
Blizzard’s model has been that the battle pass can be completed by everyone, and the season journey is more challenging because it rewards a title. People value the title more if it’s harder to get.
Based on what we’ve seen so far, I don’t think it’s reasonable to expect that everyone who makes level 100 will easily be able to complete the season journey. Blizzard seems fine with the completion percentage on it being low.
I’ll probably make a bash barb… and bash my way to glory!
Bash, Bash, Bash… Bash some more… boss dead.
how much you pay for the carries at base 100 you barely tickle lilth and havent tried the other 2 yet
I think the last chapter of the Battlepass is optional and not needed to complete the cosmetics part of it. I get that one would like to finish all chapters, but the last one there is for the more skilled players. They also deserve a reward.
I don’t expect to be able to ever beat any of the pinnacle fights as they exist now. Feels like Dark Souls comes to Diablo… I’d like to complete the seasonal journey and I didn’t expect it would be gated behind such challenging content. I’m assuming this was intentional, and there is a lot of other content to enjoy in the new season, but I can’t say I’m a fan of this trend to bring the super difficult pinnacle stuff down into the realm of things you have to do to complete the season.
The season journey should be casual content, so 100% (should be the goal for Blizzard).
Some goals does not belong to this goal in the current season.
(And yes I finished it but many casuals will not be able to)
I think conquering Uber duriel or Uber Andy is inherent to the season and should be part of the season journey completion.
After two weeks on my necro I’m able to solo Uber duriel. If you group with anyone you can easily do Duriel or Andy. I don’t think it’s unobtainable in a reasonable amount of game time.
Uber Lilith though would be an unfair expectation with the amount of learning and one shots that fight has. Equally a 200 pit would be obviously unfair for a season journey.
That is to say both tormented Duriel/Andy are fair challenges for the hoi polloi.