Overall, I also believe in the old school of thought, where bowler's main job is to win matches with the ball and they shouldn't be blamed at all if they fail to score runs.
Having said that, in modern cricket, dynamics have changed and new realities demand one extra skill from each player. For example; We expect WK to be good with the bat, previously that wasn't the case. Similarly, Bowlers need to pick up another skill as well. No one asking them to bat like a top order but they should be capable enough to strike a ball or at least rotate a strike.
Another fine example is look at the Indian WC squad. Chahal is a fine wrist spinner in White ball cricket but he didn't make it into the squad. On the other hand, Shardul (alright bowler/golden arm) and Axar (above average) got in because they know how to bat.
*Not bringing part time bowling skills from the specialist batters in this discussion atm, which is also very important.
I am not sure whether this is an apple to apple comparison. Shardul is in the team primarily because he is a good bowler. When we compare Shardul's bowling with that of Prasidh Krishna or Arshdeep Singh, he would rank at the same level, or even higher. And then he is a much better batsmen compared to either of these two, and as a result of that gets selected as the first preference. Axar is also in the same category, when we compare him with Chahal or Washington Sundar. Afghanistan doesn't have that luxury. For them, Mujeeb is one of the backbones of spin bowling. Other options such as Qais Ahmad and Izharulhaq Naveed are either at the same level in batting, or even worse. And the same argument goes for Fazalhaq Farooqi. He is not a worse batsmen, when compared to Naveen-ul-Haq or Yamin Ahmadzai.
I understand where you are coming from and that's exactly i mentioned white ball cricket. Your opinion might be clouded by their performance in red ball cricket where both of these guys (Shardul and Axar) won matches for India (if we go by our test cricket discussion, you don't consider them talented enough). My opinion of them is bit nuance and based on merits and format.
Shardul- In the away test he's the possibly best all-rounder for India after Pandya when it comes to seam wicket (SENA). Although if it's up to me then i'd still prefer Ashwin overall because he's the best off spinner in this decade and if i dare to say then maybe cricket history (it's justthat leggies are more celebrated and hyped because they are hard to develop). I might sound biased when bringing Ashwin here but at the same i am also biased for Shardul when it comes to test cricket. In ODI Thakur is handy with both ball and bat. I respect him a lot not because of his talent but his attitude of "never back down". He's literally our workhorse and not to mention our golden arm, he does unexpected things hence the tag of Lord Thakur.
Axar - He singlehandedly won a series, more importantly, broke the morale of the English team in their last tour of India and bailed out with the bat India plenty of times in his limited test career. In white ball cricket, he's a handy cricketer and he can win you matches with the bat if there is a tough situation but you have to remember he's a Jadeja like to like replacement in every format. Both of these guys bring almost similar skills to the table.
Chahal He's liability on field and we are virtually fielding 10 members playing XI when it comes to batting but he's a genuine wicket taker in white ball cricket. You mix him up with the Kuldeep and you have a perfect spin combination in the middle overs when you are bowling. This kulcha combination won us plenty of matches but they failed in the Champions Trophy final and everything changed for both of them.
Tldr : In white ball cricket Chahal is far superior bowler but a liability in batting and fielding, hence he's out.