Interesting article. Leaving out parts of the ALU seems like a common cost saving strategy.

On October 21, 1959 IBM introduced the 1620 Model I, it lacked a conventional ALU and arithmetic was done by memory table lookup. It's product code name was CADET, jokingly meaning "Can't Add, Doesn't Even Try". It was still legendary in the 1980's when I studied computer science as an example of an radical cost reduction by eliminating components.

Internal data representation

Self-checking, six-bit, binary-coded decimal.Four-bit numerical value (1-2-4-8)
Flag-bit for field and sign designation.
Check-bit to give odd parity check.

Direct conversion from card code to two-digit alphameric coding.
Processing speeds

Fixed point operations
Basic machine cycle was 21 microseconds. Time included the fetching of two factors and was the complete interval elapsed from one instruction to the next.

Addition or subtraction (5 digits) - 560 microseconds. A rate of 1,780 per second.
Multiplication (5 digits by 5 digits) - 4.96 milliseconds. A rate of 200 per second.
Division (5-digit quotient) with automatic divide feature - 16.86 milliseconds. A rate of 56 per second.
Logical decisions - 200 microseconds. A rate of 5,000 per second.
Data transmission of 5-digit fields - 360 microseconds. A rate of 2,800 per second.

Optional automatic floating point operations
When using this hardware feature, floating point numbers consisted of a variable length mantissa with a two digit exponent. So that the required degree of precision could be specified, the mantissa could vary from 2 to 100 digits in length and the exponent field could range from -99 to + 99.
The times listed are based on a two-digit exponent and an eight-digit mantissa. They include normalizing and access to two floating point fields.

Floating add or subtract — l.2 milliseconds.
Floating multiply — 12.5 milliseconds.
Floating divide — 41.7 milliseconds.
Components

IBM 1620 Central Processing Unit
Contains console, arithmetic and logical unit, and core storage.

Console

Visual display of machine check indicators, program registers and storage locations.
Control keys and switches for manual and semiautomatic control of computer operations.
Typewriter and typewriter release/start key for simultaneous release and start were included as part of the console. It functioned as a direct input-output device.

Arithmetic and logical unit

Two-address instruction format, 12 digits.
32 powerful commands — could be expanded to 47 with optional features.
Addition, subtraction and multiplication accomplished by automatic table lookup in core storage.
Division accomplished by available subroutine or by optional automatic divide feature.
Console switches and machine check indicators could be interrogated by the program.

Core storage

A basic system contained 20,000 digits of core storage.
Each digit position individually addressable by a five-digit address.
300 positions permanently assigned for use in arithmetic operations.

the SERV RISC-V design, which has a 1-bit serial ALU in order to keep the gate count way low

Leaving out parts of the ALU seems like a common cost saving strategy.