Overall, I agree with you, but–based on the OP’s description of the "problem–it didn’t need any engine repairs, and even installing a remanufactured engine would be unnecessary… IMO.
If that shop botched a simple valve cover gasket replacement, imagine what they’d do to an engine swap!
Remember that the OP replaced the tires, tie rod end and alignment and possibly other non engine related parts…
I’ve sold $4K tickets before just on wear and tear items, it can add up quickly sometimes depending on what all it needs on 20-30+ years old vehicle…
Properly done DIY repairs are always much much cheaper…
In my experience, many diy-guys use low-quality parts for their services and repairs
Correct, hence the properly done part… But I also know some DIYer’s that only use dealer or top tier parts… On the flip side, some pro shops use the cheapest parts available to increase their profit margin…
Over on TW, dealer parts are used by DIYer’s a lot of the time, certain Toyota dealers do a ton of manufacture sales (25% off) on top of the already online discounted price (ends up being close to 50% off MSRP), I buy Toyota oil filers and oil and some parts cheaper than I can aftermarket parts… the catch is most of the time you have to order $75 worth to get free shipping, now if you are close to one of the dealers that do the online sales (none anywhere close to me) just go pick it up, so you just have to plan ahead a little, I have wipers and filters in stock now for when I need them… I don’t know if any other manufacture dealer to this type of thing or not… Here is my last order from April 6 2026…
BTW, many times you can buy from the dealer this way even cheaper than buying from Amazon, and this way, no counterfeit parts… 
I don’t use cheap parts. I rarely if ever will buy parts from placed like ADAP or Advance Auto. Quality oil and oil filters. I rarely use dealer parts, but the parts I do use are as good or better.
Back around 20 years ago, the Honda dealership in Jersey City, NJ was owned by a couple of larcenous brothers. It took a while for the AG’s office to figure out what they were doing, but here is their nasty MO:
There was a Pep Boys store located across the highway from the Honda dealership. When new cars would arrive from the factory, the dealership’s mechanics would swap the OEM tires, spark plugs, and batteries for Pep Boys’ cheapest tires & batteries, and white box spark plugs. Then the dealership would sell the OEM parts at their parts counter for a nice profit.
Apparently, this scheme went on for several years until an honest indy mechanic noticed the odd parts on a disabled nearly-new Honda that had been towed to his shop. He tipped-off the car’s owner, and the motorist filed a complaint with the state’s Division of Consumer Affairs. The AG’s office purchased a new Honda from that dealership, and they confirmed the illegal substitution of parts on that vehicle. The AG’s Office placed newspaper ads asking other people to come forward, and with ample evidence of this scheme, those two guys were convicted in State Superior Court, although I don’t recall the specific charge.
After the feces hit the fan, Honda cancelled the franchise that had been held by those two crooks.
Posssibly the camshaft seals are leaking. It’s a common problem when they are replaced.